Algae issues? Why dont more people use algae scrubbers?

[ingchr1]

Well, thanks to nothing in this post (lol) I bought two Geo scrubbers that will be here this week. Happy holidays all!

Reading through this thread I think I'm going to turn my homemade scrubber back off. I just turned it back on a couple of weeks ago, and algae is just starting to grow on the screen.

 

[VintageReefer]

Reading through this thread I think I'm going to turn my homemade scrubber back off. I just turned it back on a couple of weeks ago, and algae is just starting to grow on the screen.

Sounds like it’s working. What made you initially decide to turn it on, and what’s making you think you should turn it off ?

 

[Seansea]

Reading through this thread I think I'm going to turn my homemade scrubber back off. I just turned it back on a couple of weeks ago, and algae is just starting to grow on the screen.

This thread madebyou think turn it off? You like hair algae smothering your corals in the DT?

 

[VintageReefer]

This thread madebyou think turn it off? You like hair algae smothering your corals in the DT?

I don’t get it either. Maybe I missed something

Two pics:
Scrubber broke
Scrubber fixed

Disregarding the corals that grew or were added…the green palythoa colony had hair algae literally growing out of it. The rocks had algae growing on them. All I did was replace an air pump

 

[Seansea]

I don’t get it either. Maybe I missed something

Two pics:
Scrubber broke
Scrubber fixed

Disregarding the corals that grew or were added…the green palythoa colony had hair algae literally growing out of it. The rocks had algae growing on them. All I did was replace an air pump

Man anybody who has doubts need look no further than these pics.

 

[VintageReefer]

Ill make it a little easier to see the results. Pics closer together. I dug in my album

These pics are 17 days apart and I did nothing except replace the air pump. There is still a little hair algae left under the paly colony but as you can see, the progress is undeniable

I also took a pic of the first harvest after replacing the air pump. I believe in the 17 days I only harvested once. And then I harvested again about two weeks later



Analyzing further, you can see what I mean by it fixing my rocks that were phosphate bound. The area under the palythoa. After the scrubber eliminated the free growing algae you can see, which was easy because it’s out in the water column, it started to work on future algae problems, by pulling phosphates out of the rock. In the first pic this area doesn’t have algae and in the second pic it does have some algae.

As these new phosphates leached out they became exposed to light and flow, and they did develop into small new tufts of hair algae, which the scrubber quickly eliminated also.

Once the new tufts were gone, the tank was cleaned and the algae did not return

 

[VintageReefer]

17 days. No chemicals. No water changes. No fish or creatures to eat the algae. No skimmer. No removing rocks to clean them. No gfo, chemicals, mystery products or additives of any kind. Absolutely nothing except replace the air pump on my scrubber, sit back and wait 17 days

 

[Troylee]

Correct... so hypothetically, how much or how big of a ats would it take for a 180g system with about 1000w of lighting to be out competed? Is it feasible? (In your, or anybody else's opinion)

Same.. 1000w sitting over 300 gallons lol. Zero algae.

 

[ScubaSkeets]

Ok so, in my opinion, you haven't beat algea in display with ats.. you may have made significant ground gaining control of it, but its there in a significant way. The ats is a tool in the bag, not a solution. Right? I haven't cleaned my glass in like 2 months or I would show clean seasoned rock under white light. Many of the people contesting your premise can show even cleaner/better. They are trying to guide you to the next level, not attack you. Ask for pics and be amazed

I already replied to this but I wanted to add something (rather than just edit what I already wrote)

When I cranked those white lights up, I saw the ugly green rock, just like everyone else did.
However, I still posted them without hesitation and without commenting on the green rock.
Why? Because it STILL supports my argument that the ATS works and works great. There is ABSOLUTELY no GHA or little tufts of whatever that dense mossy algae is called.
For those who didn't read this already, I have literally pressure washed those rocks several times before and while the GHA and tufts of other algae was gone, the rocks were still green.
For those who have pools, you will know that algae stains are very difficult to remove, even in a chlorinated pool.

 

[mizimmer90]

Get ready for disappointment! There is very little science being done and presented around ATS - and most of that is from people that disagree with some claims. Which is backwards in my view . The people making the claims should be supporting the claims. All to often, this is not the case. Marketing claims sound sciency, and there is great access to researchers and pubic aquarists in our hobby, but that doesn't mean that hobby science is being done. Marketing claims people want to be true because they claim to make the hobby easy get accepted based mostly on a idea of why they might work and a few testamonials (while testamonials of non support are ignored or dismissed), arguments as to why those claims may be problematic get met with outright anger. It gets old being told that I should do more science or shut up, when the initial science around a product is so lacking. There is also virtually no data about ATS in aquaria.

Yes. I would push on the people making the product and saying what it does to explain and support their theories and claims.

Not really, though that has been much of what this discussion has been about.
I don't see complelling evidence to support the idea that if you grow algae in one place in an aquarium system that it stops algal growth in another part of the system. I also don't see compelling theoritical evidence that algae growing in one part of the system can remediate an algae problem in another part of the system - that is not what happens at all on wild reefs, and algae is not 'filtration' for wild reefs. Additionally, I don't see compellling evidence that low 'nutrients', mostly people talk about nitrate and phosphate, are necessary for a reef tank or that they contribute to faster growth of algae in peoples tanks. Talks and articles are online, they lay out what I think and why, and some more recent stuff is directly about algae management in our tanks, and lay out evidence for why if photosynthetic corals can grow, algae can grow. R2R sometimes gets grumpy when I link stuff, so I can't link them for you but my website is in my sig if you are interested.
I don't use ATS mostly because I don't see a need to lower nitrate and phosphae and I don't have algae problems. When I have used ATS, and have done everything the people making the ATS have told me to do, the results are not what they said they would be - and then I get told that I have to set up the ATS differently. After making those changes, it still doesn't do much, I get told to do it differently yet again. This is more work than I think is reasonable to try to support someone else's claim about their product, espically when the central claim of the product seems to revolve around how easy it is to use. My testimonial about ATS, and others that have similar experiences, are largely ignored, even though there seem to be at least equal amounts of both testimonials.
I don't feel the need to make the changes in my system that most ATS makers say folks need to make, testing more products who's claims don't seem well supported beyond testamonials isn't that attractive to me. It's been at least 15 years (close enough) since ATS were introduced, and I think there should be more support for the claims by now. I am friends with one ATS maker that has been doing a lot of good science around ATS (he does not make the post hoc propter hoc claim that his units will stop algae from growing in other parts of the system), so I think about trying one of his units from time to time, but since I don't need to 'fix' my nirtate and phosphate levels, I don't have an algae problem, I have trouble wanting to spend the money and time on an ATS....again.

Hope your Monday is going well!

Get ready for excitement! I'll demonstrate the power of a good model!

To alleviate confusion around this, I decided to model the effect of a refugium/ATS and prove that growing algae in one location will have an effect on the amount of algae grown at a different location (and even has the ability to make it go to 0).

Consider the following setup of a display tank and a refugium/ATS with volumes of V0 and V1, respectively.

The Nutrients (N) in the tank are considered "well mixed", which means that the concentration is instantaneously equilibrated, and local effects are not considered, i.e. algae in the display has access to the identical nutrients in the refugium/ATS and vice versa. p0 and p1 are intrinsic rates of nutrient intake per unit volume for the display tank algae and fuge/ATS algae, respectively (these values are different because of lighting power/spectrum differences, etc. but could also be more general to measure of other factors too).

With this setup, we can model a set of differential equations that describes the change in nutrients in the water column, as well as nutrients that accumulate in algae from the display tank or fuge/ATS.

Here, N(t) is the amount of nutrients in the water column, A0 is the amount of algae in the display, and A1 is the amount of algae in the refugium (both A0 and A1 are in units of nutrients). We can also model a constant influx of nutrients to the tank (i.e. through feeding). In this model, I assume no outflow of nutrients, so the sum of N, A0, and A1 is always increasing by c*t.

Solving these differential equations for N, A0, and A1 yields the following:

Now the neat thing about this is that the growth of algae in the display is proportional to the ratio of intrinsic growth of the display and its volume by the total algal growth (p0V0 / (p0V0 + p1V1)). If we take this to the limits and have a significantly larger Fuge/ATS than the display tank, we can see the algae growth in the display tank goes to zero!

This is a proof that your model is wrong! Algae grown in one side of the tank *DOES* influence algae grown at another, and a sufficiently large fuge/ATS *CAN* completely outcompete algae in the display.

So, finishing our discussion: if a fuge/ATS doesn't work, it's NOT because algae grown at one location can't compete with another location.

Backing up though, how many of us have a fuge/ATS that's larger than our tank?? I doubt many! So what might these curves look like in practice? Well, I computed the nutrient/algae growth as a function of time from the above derivations and there's some informative data!

First, imagine we have a fuge the same size at the display, with identical lighting power/spectrum. Both A0 and A1 curves are the same (green and red respectively, though green is completely overlapped by red in this plot; free nutrients as black curve) and the ratio of algae in the display and in the fuge is 1 (seems reasonable!). BTW, code is in python and available on request!

Next, convincing ourselves that it's possible for a mega sized fuge (100x the display with a comparative advantage of 10x!) to completely out compete the display tank. A0/A1 ratio is 0.001(this value actually just ends up being the ratio of (P0V0)/(P1V1) so I'm dropping it from subsequent plots.

Okay, I know you're saying this isn't realistic! So what about a fuge that's half the size of the display (still a big fuge) with lights that give a 10x advantage (this is a guess but we can throw this parameter around). Doesn't look too bad! definitely helps, but this model predicts significant algae still growing in the display (green curve).

What about a significantly smaller ATS (5% of tank volume) with bigger advantages (50x comparative advantage to display)? Similar split.

What if we have an underpowered fuge/ATS? lets say same size as above but only a 10x advantage to the display?

Now the algae in the display starts to win! Though its important to notice that the display algae is still much lower than it would be without the fuge/ATS.

Now, I wouldn't read into exact values (a little arbitrary), but this shows how we can tune the knobs of our system and how it will influence the tank!

Summarizing the whole discussion, this model is actually *consistent* with a lot of what you say and actually serves to validate your experience. It's clear that in some circumstances, an ATS and fuge is not "all you need" (though to be fair I'm not sure anyone has actually ever said that in this thread lol).

It is consistent that even with an ATS, you and others can still see algae in your display tanks. However, it is clear that an ATS can work, but might need to be supplemented with some other practices that add to the comparative advantage, like... herbivores!

The big difference, and the reason I've been persistent is that your explanation of "why" just didn't hold water (pun intended lol).

I hope you have a great Tuesday!

 

[mizimmer90]

Get ready for excitement! I'll demonstrate the power of a good model!

To alleviate confusion around this, I decided to model the effect of a refugium/ATS and prove that growing algae in one location will have an effect on the amount of algae grown at a different location (and even has the ability to make it go to 0).

Consider the following setup of a display tank and a refugium/ATS with volumes of V0 and V1, respectively.

The Nutrients (N) in the tank are considered "well mixed", which means that the concentration is instantaneously equilibrated, and local effects are not considered, i.e. algae in the display has access to the identical nutrients in the refugium/ATS and vice versa. p0 and p1 are intrinsic rates of nutrient intake per unit volume for the display tank algae and fuge/ATS algae, respectively (these values are different because of lighting power/spectrum differences, etc. but could also be more general to measure of other factors too).

With this setup, we can model a set of differential equations that describes the change in nutrients in the water column, as well as nutrients that accumulate in algae from the display tank or fuge/ATS.

Here, N(t) is the amount of nutrients in the water column, A0 is the amount of algae in the display, and A1 is the amount of algae in the refugium (both A0 and A1 are in units of nutrients). We can also model a constant influx of nutrients to the tank (i.e. through feeding). In this model, I assume no outflow of nutrients, so the sum of N, A0, and A1 is always increasing by c*t.

Solving these differential equations for N, A0, and A1 yields the following:

Now the neat thing about this is that the growth of algae in the display is proportional to the ratio of intrinsic growth of the display and its volume by the total algal growth (p0V0 / (p0V0 + p1V1)). If we take this to the limits and have a significantly larger Fuge/ATS than the display tank, we can see the algae growth in the display tank goes to zero!

This is a proof that your model is wrong! Algae grown in one side of the tank *DOES* influence algae grown at another, and a sufficiently large fuge/ATS *CAN* completely outcompete algae in the display.

So, finishing our discussion: if a fuge/ATS doesn't work, it's NOT because algae grown at one location can't compete with another location.

Backing up though, how many of us have a fuge/ATS that's larger than our tank?? I doubt many! So what might these curves look like in practice? Well, I computed the nutrient/algae growth as a function of time from the above derivations and there's some informative data!

First, imagine we have a fuge the same size at the display, with identical lighting power/spectrum. Both A0 and A1 curves are the same (green and red respectively, though green is completely overlapped by red in this plot; free nutrients as black curve) and the ratio of algae in the display and in the fuge is 1 (seems reasonable!). BTW, code is in python and available on request!

Next, convincing ourselves that it's possible for a mega sized fuge (100x the display with a comparative advantage of 10x!) to completely out compete the display tank. A0/A1 ratio is 0.001(this value actually just ends up being the ratio of (P0V0)/(P1V1) so I'm dropping it from subsequent plots.

Okay, I know you're saying this isn't realistic! So what about a fuge that's half the size of the display (still a big fuge) with lights that give a 10x advantage (this is a guess but we can throw this parameter around). Doesn't look too bad! definitely helps, but this model predicts significant algae still growing in the display (green curve).

What about a significantly smaller ATS (5% of tank volume) with bigger advantages (50x comparative advantage to display)? Similar split.

What if we have an underpowered fuge/ATS? lets say same size as above but only a 10x advantage to the display?

Now the algae in the display starts to win! Though its important to notice that the display algae is still much lower than it would be without the fuge/ATS.

Now, I wouldn't read into exact values, but this shows how we can tune the knobs of our system and how it will influence the tank!

Summarizing the whole discussion, this model is actually *consistent* with everything you say and actually serves to validate your experience. It's clear that an ATS and fuge is *not* "all you need" (though to be fair I'm not sure anyone has actually ever said that in this thread lol).

It is consistent that even with a good ATS, you and others can still see algae in your display tanks. However, it is clear that an ATS can work, but might need to be supplemented with some other practices that add to the comparative advantage, like... herbivores!

The big difference, and the reason I've been persistent is that your explanation of "why" just didn't hold water (pun intended lol).

I hope you have a great Tuesday!

I'll just add one more thing! This model simplifies to an easy to remember paradigm, one that I insisted early on but now have a proof for: the amount of algae at each location in your tank/fuge is directly proportional to its comparative advantage!

 

[mizimmer90]

One more lol! since @ScubaSkeets @VintageReefer @jason2459 @Troylee have been so nice to share their tanks and successes, I had forgotten to mention that these results are also strongly consistent with their experiences!

An important reminder that the exact numbers entered into this derivation are arbitrary, but the math is clear that an ATS absolutely can work!

Get ready for excitement! I'll demonstrate the power of a good model!

To alleviate confusion around this, I decided to model the effect of a refugium/ATS and prove that growing algae in one location will have an effect on the amount of algae grown at a different location (and even has the ability to make it go to 0).

Consider the following setup of a display tank and a refugium/ATS with volumes of V0 and V1, respectively.

The Nutrients (N) in the tank are considered "well mixed", which means that the concentration is instantaneously equilibrated, and local effects are not considered, i.e. algae in the display has access to the identical nutrients in the refugium/ATS and vice versa. p0 and p1 are intrinsic rates of nutrient intake per unit volume for the display tank algae and fuge/ATS algae, respectively (these values are different because of lighting power/spectrum differences, etc. but could also be more general to measure of other factors too).

With this setup, we can model a set of differential equations that describes the change in nutrients in the water column, as well as nutrients that accumulate in algae from the display tank or fuge/ATS.

Here, N(t) is the amount of nutrients in the water column, A0 is the amount of algae in the display, and A1 is the amount of algae in the refugium (both A0 and A1 are in units of nutrients). We can also model a constant influx of nutrients to the tank (i.e. through feeding). In this model, I assume no outflow of nutrients, so the sum of N, A0, and A1 is always increasing by c*t.

Solving these differential equations for N, A0, and A1 yields the following:

Now the neat thing about this is that the growth of algae in the display is proportional to the ratio of intrinsic growth of the display and its volume by the total algal growth (p0V0 / (p0V0 + p1V1)). If we take this to the limits and have a significantly larger Fuge/ATS than the display tank, we can see the algae growth in the display tank goes to zero!

This is a proof that your model is wrong! Algae grown in one side of the tank *DOES* influence algae grown at another, and a sufficiently large fuge/ATS *CAN* completely outcompete algae in the display.

So, finishing our discussion: if a fuge/ATS doesn't work, it's NOT because algae grown at one location can't compete with another location.

Backing up though, how many of us have a fuge/ATS that's larger than our tank?? I doubt many! So what might these curves look like in practice? Well, I computed the nutrient/algae growth as a function of time from the above derivations and there's some informative data!

First, imagine we have a fuge the same size at the display, with identical lighting power/spectrum. Both A0 and A1 curves are the same (green and red respectively, though green is completely overlapped by red in this plot; free nutrients as black curve) and the ratio of algae in the display and in the fuge is 1 (seems reasonable!). BTW, code is in python and available on request!

Next, convincing ourselves that it's possible for a mega sized fuge (100x the display with a comparative advantage of 10x!) to completely out compete the display tank. A0/A1 ratio is 0.001(this value actually just ends up being the ratio of (P0V0)/(P1V1) so I'm dropping it from subsequent plots.

Okay, I know you're saying this isn't realistic! So what about a fuge that's half the size of the display (still a big fuge) with lights that give a 10x advantage (this is a guess but we can throw this parameter around). Doesn't look too bad! definitely helps, but this model predicts significant algae still growing in the display (green curve).

What about a significantly smaller ATS (5% of tank volume) with bigger advantages (50x comparative advantage to display)? Similar split.

What if we have an underpowered fuge/ATS? lets say same size as above but only a 10x advantage to the display?

Now the algae in the display starts to win! Though its important to notice that the display algae is still much lower than it would be without the fuge/ATS.

Now, I wouldn't read into exact values, but this shows how we can tune the knobs of our system and how it will influence the tank!

Summarizing the whole discussion, this model is actually *consistent* with everything you say and actually serves to validate your experience. It's clear that an ATS and fuge is *not* "all you need" (though to be fair I'm not sure anyone has actually ever said that in this thread lol).

It is consistent that even with a good ATS, you and others can still see algae in your display tanks. However, it is clear that an ATS can work, but might need to be supplemented with some other practices that add to the comparative advantage, like... herbivores!

The big difference, and the reason I've been persistent is that your explanation of "why" just didn't hold water (pun intended lol).

I hope you have a great Tuesday!

 

[Shon]

Growing turf algae in a scrubber = it won’t help, it doesn’t work, you can’t feed it to fish

When I had the 75 fowlr going, I used to take a large marble size of squeezed out hair algae and drop it in my fresh water tanks. One tank, ~20 mollies would make short work of it. Same with the mystery snail breeding tank and ramshorn breeding tank. Though the snails took longer to get around to it, still ate it with gusto. Did that every few days. Dropped overall cost with feeding since canned green beans I have to buy as algae is free.

 

[WhatCouldGoWrong71]

I brought extra in case anyone wants some

 

[Garf]

Get ready for excitement! I'll demonstrate the power of a good model!

To alleviate confusion around this, I decided to model the effect of a refugium/ATS and prove that growing algae in one location will have an effect on the amount of algae grown at a different location (and even has the ability to make it go to 0).

Consider the following setup of a display tank and a refugium/ATS with volumes of V0 and V1, respectively.

The Nutrients (N) in the tank are considered "well mixed", which means that the concentration is instantaneously equilibrated, and local effects are not considered, i.e. algae in the display has access to the identical nutrients in the refugium/ATS and vice versa. p0 and p1 are intrinsic rates of nutrient intake per unit volume for the display tank algae and fuge/ATS algae, respectively (these values are different because of lighting power/spectrum differences, etc. but could also be more general to measure of other factors too).

With this setup, we can model a set of differential equations that describes the change in nutrients in the water column, as well as nutrients that accumulate in algae from the display tank or fuge/ATS.

Here, N(t) is the amount of nutrients in the water column, A0 is the amount of algae in the display, and A1 is the amount of algae in the refugium (both A0 and A1 are in units of nutrients). We can also model a constant influx of nutrients to the tank (i.e. through feeding). In this model, I assume no outflow of nutrients, so the sum of N, A0, and A1 is always increasing by c*t.

Solving these differential equations for N, A0, and A1 yields the following:

Now the neat thing about this is that the growth of algae in the display is proportional to the ratio of intrinsic growth of the display and its volume by the total algal growth (p0V0 / (p0V0 + p1V1)). If we take this to the limits and have a significantly larger Fuge/ATS than the display tank, we can see the algae growth in the display tank goes to zero!

This is a proof that your model is wrong! Algae grown in one side of the tank *DOES* influence algae grown at another, and a sufficiently large fuge/ATS *CAN* completely outcompete algae in the display.

So, finishing our discussion: if a fuge/ATS doesn't work, it's NOT because algae grown at one location can't compete with another location.

Backing up though, how many of us have a fuge/ATS that's larger than our tank?? I doubt many! So what might these curves look like in practice? Well, I computed the nutrient/algae growth as a function of time from the above derivations and there's some informative data!

First, imagine we have a fuge the same size at the display, with identical lighting power/spectrum. Both A0 and A1 curves are the same (green and red respectively, though green is completely overlapped by red in this plot; free nutrients as black curve) and the ratio of algae in the display and in the fuge is 1 (seems reasonable!). BTW, code is in python and available on request!

Next, convincing ourselves that it's possible for a mega sized fuge (100x the display with a comparative advantage of 10x!) to completely out compete the display tank. A0/A1 ratio is 0.001(this value actually just ends up being the ratio of (P0V0)/(P1V1) so I'm dropping it from subsequent plots.

Okay, I know you're saying this isn't realistic! So what about a fuge that's half the size of the display (still a big fuge) with lights that give a 10x advantage (this is a guess but we can throw this parameter around). Doesn't look too bad! definitely helps, but this model predicts significant algae still growing in the display (green curve).

What about a significantly smaller ATS (5% of tank volume) with bigger advantages (50x comparative advantage to display)? Similar split.

What if we have an underpowered fuge/ATS? lets say same size as above but only a 10x advantage to the display?

Now the algae in the display starts to win! Though its important to notice that the display algae is still much lower than it would be without the fuge/ATS.

Now, I wouldn't read into exact values (a little arbitrary), but this shows how we can tune the knobs of our system and how it will influence the tank!

Summarizing the whole discussion, this model is actually *consistent* with a lot of what you say and actually serves to validate your experience. It's clear that in some circumstances, an ATS and fuge is not "all you need" (though to be fair I'm not sure anyone has actually ever said that in this thread lol).

It is consistent that even with an ATS, you and others can still see algae in your display tanks. However, it is clear that an ATS can work, but might need to be supplemented with some other practices that add to the comparative advantage, like... herbivores!

The big difference, and the reason I've been persistent is that your explanation of "why" just didn't hold water (pun intended lol).

I hope you have a great Tuesday!

So, in this extreme model, anything in the display that’s photosynthetic would die? I don’t think that’s the aim at all.
Of course it’s a lot more complicated than this in reality. There’s photinhibition (unknown in most cases) and saturation rates of algae (which may be close to saturation already, but for all practicality for us, unknown), shading ((the algae on my ATS screen was only sufficiently lit for 30 to 50% of the cycle, but variable depending algal thickness and pigmentation), light source PUR), sedimentation, the release of algal exudates (10 to 40% of productivity), unknown direct interactions with released algal compounds in a closed system, unknown bacteria interactions in a closed system powered by exudates, to name a few. Can you even model anything when the equations include 2 or more “ Unknowns “, surely the interactions convert it to a 3 body problem? Aside from that, try adding a regular influx of nutrients into the display tank, which would also be variable, and as far as scrubbers would be concerned, so would the “filters” contact time depending upon flow to and from the “filter” from the display tank. I do appreciate that you’ve made so much effort on this model by the way.

 

[mizimmer90]

So, in this extreme model, anything in the display that’s photosynthetic would die? I don’t think that’s the aim at all.

No, my model does not predict that anything photosynthetic would die! The model is focused on competition for nutrients in the water column, specifically the nutrients that are rate limiting. Lighting is fixed here and I have included a constant influx of new nutrients into the tank (df/dt in above).

In my model nutrients do not go to 0 because of the nutrients constantly being added to the tank. As such, we would expect corals to still grow, but algae will be limited and not able to bloom at some point (when the concentrations of rate limiting nutrients get low enough)

Of course it’s a lot more complicated than this in reality. There’s photinhibition (unknown in most cases) and saturation rates of algae (which may be close to saturation already, but for all practicality for us, unknown), shading ((the algae on my ATS screen was only sufficiently lit for 30 to 50% of the cycle, but variable depending algal thickness and pigmentation), light source PUR), sedimentation, the release of algal exudates (10 to 40% of productivity), unknown direct interactions with released algal compounds in a closed system, unknown bacteria interactions in a closed system powered by exudates, to name a few. Can you even model anything when the equations include 2 or more “ Unknowns “, surely the interactions convert it to a 3 body problem? Aside from that, try adding a regular influx of nutrients into the display tank, which would also be variable, and as far as scrubbers would be concerned, so would the “filters” contact time depending upon flow to and from the “filter” from the display tank.

This is definitely a first order approximation and I wouldn't read into the exact input and output values but the trends are rock solid! Changing the kinetics from first order to higher levels or adding in fudge factors will slightly change the shapes of the curves but the trends will be the same!

I do appreciate that you’ve made so much effort on this model by the way.

Thank you!

 

[BeanAnimal]

And I don’t know about their current relationship today but Santa Monica is one of the original designers of the scrubbers and has many patents but originally back in 2012 while making new designs he gave them out to free to the community to use and make their own at home and who was one of the people that was on the forum and getting the design ideas, collaborating, and providing insight and advice - Floyd Turbo.

Waterfall scrubbers have water flowing down a screen and Santa Monica invented and patented the upflow design to reduce noise, where water flows up or though a screen using bubbles.

Patents or not, I don't remember it being that cut and dry or glossy and while SM may have worked very hard to build a patentable product, he didn't invent turf scrubbing and in fact there were plenty of us prior to 2012 using ATS in various forms.

Prior to buckets and clip on shop lights, many of ran dump boxes either DIY or commercial units. Dr. Walter Adey coined the term and started working on these and publishing articles about "Algal Turf Scrubbers" in the late 70s and had a patent by 1982.

I had an an Adey ATS sometime in the early 2000's and grew wary of keeping it the dump tray rocking and simply ran it in a fixed position with a better light. Many of us did the same thing. So sure, SM b

 

[mizimmer90]

I'll give a little more detail on these points because I think they're good!

There’s photinhibition (unknown in most cases) and saturation rates of algae (which may be close to saturation already, but for all practicality for us, unknown), shading ((the algae on my ATS screen was only sufficiently lit for 30 to 50% of the cycle, but variable depending algal thickness and pigmentation), light source PUR), sedimentation, the release of algal exudates (10 to 40% of productivity), unknown direct interactions with released algal compounds in a closed system, unknown bacteria interactions in a closed system powered by exudates, to name a few.

These are all good effects and my model wraps them all into this "intrinsic growth rate per unit volume". This term is an amalgam of all the (non nutrient) effects that contribute to the growth of algae at that spot and can be generalized to include lighting, position, allopathic effects, herbivores etc.

Can you even model anything when the equations include 2 or more “ Unknowns “, surely the interactions convert it to a 3 body problem?

We can solve for the relations between the variables and model what the curves look like under different conditions (a type of simulation). That's what the curves demonstrate below the model!

Aside from that, try adding a regular influx of nutrients into the display tank, which would also be variable

As mentioned in the first reply, this is already included with df/dt and is assumed to be a constant rate of nutrient influx.

and as far as scrubbers would be concerned, so would the “filters” contact time depending upon flow to and from the “filter” from the display tank.

This is certainly an effect but my model assumes that the tank is rapidly mixed. I think it's a reasonable approximation since the flow inside/through tanks, temperature/diffusion times would mix the nutrients faster than they will be depleted.

I do appreciate that you’ve made so much effort on this model by the way.

And thanks again for reading this and giving feedback!!

 

[Garf]

Patents or not, I don't remember it being that cut and dry or glossy and while SM may have worked very hard to build a patentable product, he didn't invent turf scrubbing and in fact there were plenty of us prior to 2012 using ATS in various forms.

Prior to buckets and clip on shop lights, many of ran dump boxes either DIY or commercial units. Dr. Walter Adey coined the term and started working on these and publishing articles about "Algal Turf Scrubbers" in the late 70s and had a patent by 1982.

I had an an Adey ATS sometime in the early 2000's and grew wary of keeping it the dump tray rocking and simply ran it in a fixed position with a better light. Many of us did the same thing. So sure, SM b

He patented “bubbles” as a method of circulation in regard to growing algae on a screen, as far as I remember.

 

[BeanAnimal]

Get ready for excitement! I'll demonstrate the power of a good model!

To alleviate confusion around this, I decided to model the effect of a refugium/ATS and prove that growing algae in one location will have an effect on the amount of algae grown at a different location (and even has the ability to make it go to 0).

Consider the following setup of a display tank and a refugium/ATS with volumes of V0 and V1, respectively.

The Nutrients (N) in the tank are considered "well mixed", which means that the concentration is instantaneously equilibrated, and local effects are not considered, i.e. algae in the display has access to the identical nutrients in the refugium/ATS and vice versa. p0 and p1 are intrinsic rates of nutrient intake per unit volume for the display tank algae and fuge/ATS algae, respectively (these values are different because of lighting power/spectrum differences, etc. but could also be more general to measure of other factors too).

With this setup, we can model a set of differential equations that describes the change in nutrients in the water column, as well as nutrients that accumulate in algae from the display tank or fuge/ATS.

Here, N(t) is the amount of nutrients in the water column, A0 is the amount of algae in the display, and A1 is the amount of algae in the refugium (both A0 and A1 are in units of nutrients). We can also model a constant influx of nutrients to the tank (i.e. through feeding). In this model, I assume no outflow of nutrients, so the sum of N, A0, and A1 is always increasing by c*t.

Solving these differential equations for N, A0, and A1 yields the following:

Now the neat thing about this is that the growth of algae in the display is proportional to the ratio of intrinsic growth of the display and its volume by the total algal growth (p0V0 / (p0V0 + p1V1)). If we take this to the limits and have a significantly larger Fuge/ATS than the display tank, we can see the algae growth in the display tank goes to zero!

This is a proof that your model is wrong! Algae grown in one side of the tank *DOES* influence algae grown at another, and a sufficiently large fuge/ATS *CAN* completely outcompete algae in the display.

So, finishing our discussion: if a fuge/ATS doesn't work, it's NOT because algae grown at one location can't compete with another location.

Backing up though, how many of us have a fuge/ATS that's larger than our tank?? I doubt many! So what might these curves look like in practice? Well, I computed the nutrient/algae growth as a function of time from the above derivations and there's some informative data!

First, imagine we have a fuge the same size at the display, with identical lighting power/spectrum. Both A0 and A1 curves are the same (green and red respectively, though green is completely overlapped by red in this plot; free nutrients as black curve) and the ratio of algae in the display and in the fuge is 1 (seems reasonable!). BTW, code is in python and available on request!

Next, convincing ourselves that it's possible for a mega sized fuge (100x the display with a comparative advantage of 10x!) to completely out compete the display tank. A0/A1 ratio is 0.001(this value actually just ends up being the ratio of (P0V0)/(P1V1) so I'm dropping it from subsequent plots.

Okay, I know you're saying this isn't realistic! So what about a fuge that's half the size of the display (still a big fuge) with lights that give a 10x advantage (this is a guess but we can throw this parameter around). Doesn't look too bad! definitely helps, but this model predicts significant algae still growing in the display (green curve).

What about a significantly smaller ATS (5% of tank volume) with bigger advantages (50x comparative advantage to display)? Similar split.

What if we have an underpowered fuge/ATS? lets say same size as above but only a 10x advantage to the display?

Now the algae in the display starts to win! Though its important to notice that the display algae is still much lower than it would be without the fuge/ATS.

Now, I wouldn't read into exact values (a little arbitrary), but this shows how we can tune the knobs of our system and how it will influence the tank!

Summarizing the whole discussion, this model is actually *consistent* with a lot of what you say and actually serves to validate your experience. It's clear that in some circumstances, an ATS and fuge is not "all you need" (though to be fair I'm not sure anyone has actually ever said that in this thread lol).

It is consistent that even with an ATS, you and others can still see algae in your display tanks. However, it is clear that an ATS can work, but might need to be supplemented with some other practices that add to the comparative advantage, like... herbivores!

The big difference, and the reason I've been persistent is that your explanation of "why" just didn't hold water (pun intended lol).

I hope you have a great Tuesday!

Respectfully - while a model and math can "check out" that does not mean that the model is actually realistic or nature will even be close.

For one to "outcompete" the other with a shared homogenous food supply, one would have to be more suitable for consumption. I don't think that is even remotely qualifiable with any reasonable formula for the display or the ATS.

I have played with ATSs for years. Adey dump boxes (very oversized for my tank), buckets and bulbs, waterfall scrubbers and likewise various refugia which are to an extent an analog using the the same nutrients. There are times when one or the other flourish with algea, or both do. There are countless variables. I no longer run an ATS or refugium. I don't see the benefit vs trouble.