Algae issues? Why dont more people use algae scrubbers?

[jda]

Sorry for the layman's model above, but save a few of us, I think several following along could use the simplified break down.

Don't sweat this too much. I think that everybody is on the same page here save for two people.

 

[BeanAnimal]

I spend zero time growing algae. It just grows by itself in my scrubber. Once every 2 weeks I spend 30 seconds to grab a handful of algae and throw it away.

What do you do to maintain those numbers? I bet it’s more time than I spend on my tank

I ran a scrubber on and off over the last 20 years, as well as a refugium and at one point both.

IMHO - I did not feel that either provided me with a net benefit and both were expensive detritus traps and tannin factories.

I spent more money on electricity, more money on pumps and maintenance and they both significantly added to the complication of the system and failure modes.

The irony to me is that many people "feed" their ATSs and Refuges to keep them "healthy". SO much for export, now we are spending time and money growing gardens for the garbage can.

I don't think that I will ever run an refugium again. I still have large waterfall style ATS but am not sure that it will ever go back online.

 

[Thales]

I don't understand this distinction lol.

"Can" expresses ability or capability, while "may" expresses possibility.

 

[Reefering1]

"Can" expresses ability or capability, while "may" expresses possibility.

Example: the algea may thrive in a tank but can't because it gets eaten too fast..

 

[jason2459]

The irony to me is that many people "feed" their ATSs and Refuges to keep them "healthy". SO much for export, now we are spending time and money growing gardens for the garbage can.

I feed my tank. I do dose Iron and originally mainly for the ATS so I guess I do feed the ATS. I noticed improvements to things other then the ATS so kept dosing iron.

For nutrient export water changes would be a viable alternative or skimming wet. Carbon dosing is a good strategy for many with out an ATS or other algae harvesting methods. I'm sure there's many others.

I guess if going down the path of a method of dosing lots of various elements then Algae harvesting could be counter productive.

 

[BeanAnimal]

"Can" expresses ability or capability, while "may" expresses possibility.

Ohh the arguments I have had over "shall" and "may" over the years. It looks like the feds have buckled to the ignorance of language and are now officially using "must" and "may" and doing away with "shall".

 

[VintageReefer]

IMHO - I did not feel that either provided me with a net benefit and both were expensive detritus traps and tannin factories.

I spent more money on electricity, more money on pumps and maintenance and they both significantly added to the complication of the system and failure modes.

The irony to me is that many people "feed" their ATSs and Refuges to keep them "healthy". SO much for export, now we are spending time and money growing gardens for the garbage can.

I’m sorry for your experience, sounds like it is a bad design! Maybe it was functional in some ways but it doesn’t sound like yours was simple or user friendly or efficient!

Mine uses 12w of power, has no water pump, does not trap detritus (because water is not being pumped in and it uses bubbles instead from a low flow area of my sump, and if it does get any detritus somehow then it comes out with the harvest, doesn’t leach tannins, requires no maintenance or fiddling, and doesn’t need to be fed! I’ve used it for 10 years on multiple tanks and it’s been nothing but helpful and productive! Plug and Play! Yes I throw the algae away, but I grow it for free, I be never had to dose anything to fertilize it, and people throw away chaeto all the time in regular refugiums.

If you ever decided to try one again I would suggest a upflow style instead of the waterfall design. You might have a different experience and be impressed

 

[GARRIGA]

Can May Shall

Flashes of tall lady with ruler about to smack my digits what that dredged up

 

[mizimmer90]

Sorry for the layman's model above, but save a few of us, I think several following along could use the simplified break down.

Absolutely! Thanks for the feedback and I really appreciate you taking the time to consider this! I completely agree that I need to give some more clarification on this model and how it works!

I think we all agree that the two areas will compete with each other for nutrients with a demand ratio (in a well mixed system) based on the suitability of each area. Bit I don't think we can easily define the competition or the result of that competition. In other words, I don't feel the model fits even if it is pretty and tidy and the equations balance.

1 - If we take one area or the other away, (let's say that one produces 5 units of algae per time and the other 3 units per time. We don't magically end up with the leftover area producing 8 units per time. In fact, it may still only produce its 5 units (or 3 or whatever). We don't know because nutrient availability is not the only limiting variable in each area and light, flow, surface texture, predation, local competition between already dominant or established species, etc. come into play.

2 - In a similar fashion if we start with an area (display) that produces 5 units of algae per time. Adding an ATS that is capable of 10 units of export at a time does not mean that it will produce 5 and the system will be at zero. What will the ratio be? 2.5:2.5 or 3:2. etc, or will there even be 5 units produced?

Sorry for the layman's model above, but save a few of us, I think several following along could use the simplified break down.

This is a good point and I'll take this as an opportunity to elaborate on the assumptions in the model

The first assumption is that the rate of change of algae growth is not constant with time, but that it is proportional with the amount of nutrients in the tank. That means that as the nutrients go down, the rate of algae growth goes down too. As the nutrients go up, the rate of algae growth goes back up. The rate scales linearly with “nutrients”, which is a kind of first order rate. 0th order would mean the rate is constant, no matter what, a 2nd order would scale quadratically with the nutrients, etc. A 0th order reaction is always an approximation based on artifacts of the starting conditions, and it's not applicable in this case. The alternative would be higher order reactions but the end results have roughly the same trends.

The next assumption is that while the rate of algae growth is proportional with nutrients, it's scaled by the intrinsic factors of a particular site. These factors include things like lighting, spectrum, location, water flow, etc. But can also take into account allelopathic effects/competition with microbes/inverts/algae eating fish. Its possible to write each of these terms out individually, but mathematically, they end up getting averaged and this notation is actually equivalent to considering them individually.

The idea is that the nutrients dictate the shape of the algae growth, but the intrinsic factors dictate the scale of the nutrient utilization. I.e. turning lights down low might have a lower intrinsic factor and thus, the rate is scaled down lower (but growth is still proportional to nutrients). I've factored out the intrinsic scale into a scale per unit volume so that it itself can be normalized by the volume that it is enacted over. The idea being that you have a tank with a particular lighting/spectrum/competition etc. and multiply this over some volume to account for effect size over an entire tank/fuge

The equation with dA/dt indicates the rate of algae growth with time. From above, it is proportional to the nutrients, but is scaled by the terms, p and V, which are constants. p can be modeled as being dependent on time (it definitely is) but this layer of complication is not necessary here because my assumption is that lighting/flow are the driving factors for most tanks and these are relatively constant (or can be averaged over some timespan)

It's important to note that the rate of algae growth in a display does NOT depend on the rate in the refugium. Therefore if you suddenly take out your fuge algae, the “instantaneous” rate of growth in your tank stays the same. But since these rates are 1st order (or higher) as the nutrients get taken in, the algae growth slows down unless more nutrients are added to refuel.

As for the total nutrients in the tank, I assume a constant influx of new nutrients (such as in the form of feedings). I.e. df/dt = a constant. The Nutrients in this model are always increasing (no water changes/removal of algae/no die off of algae). These things can be added in but again they don't change the trends and would make the notion more cumbersome.

With these assumptions, we just solve the equations for algae as a function of time for the display/fuge and the nutrients as a function of time

Since these are first order kinetics, the ratio of algae in each tank ends up being the ratio of their competitive advantages, though with higher order reactions the fractions would change somewhat

As part of my proof that algae at a distance can and does slow algae growth I show that as the comparative advantage becomes so large, algae at one location trends to 0

While the model is pretty robust to a lot of effects and trends that we will see in our tanks, I wouldn't read into the exact values of the numbers entered. If we wanted a more accurate model, to be used on a tank by tank basis, we'd need to characterize precise values of the intrinsic growth params (or actually just a good idea of the relative advantage, i.e. if we knew that the refugium was 120x better at growing algae per area than the DT). But we can use this model to predict how much the advantage needs to be to get a certain split of algae in the DT/fuge. Also we could get more accurate curves by knowing which nutrients in particular were rate limiting, and modeling the higher order reactions. It's actually feasible to do some home measurements of these without getting too complicated

I know this is a lot and I'm happy to keep discussing this! I find it really fun to talk models/theory, especially when they are useful. I'm also eager to contribute back to this community of reefers because I've learned so much on these forums.

 

[Reefering1]

Absolutely! Thanks for the feedback and I really appreciate you taking the time to consider this! I completely agree that I need to give some more clarification on this model and how it works!



This is a good point and I'll take this as an opportunity to elaborate on the assumptions in the model

The first assumption is that the rate of change of algae growth is not constant with time, but that it is proportional with the amount of nutrients in the tank. That means that as the nutrients go down, the rate of algae growth goes down too. As the nutrients go up, the rate of algae growth goes back up. The rate scales linearly with “nutrients”, which is a kind of first order rate. 0th order would mean the rate is constant, no matter what, a 2nd order would scale quadratically with the nutrients, etc. A 0th order reaction is always an approximation based on artifacts of the starting conditions, and it's not applicable in this case. The alternative would be higher order reactions but the end results have roughly the same trends.

The next assumption is that while the rate of algae growth is proportional with nutrients, it's scaled by the intrinsic factors of a particular site. These factors include things like lighting, spectrum, location, water flow, etc. But can also take into account allelopathic effects/competition with microbes/inverts/algae eating fish. Its possible to write each of these terms out individually, but mathematically, they end up getting averaged and this notation is actually equivalent to considering them individually.

The idea is that the nutrients dictate the shape of the algae growth, but the intrinsic factors dictate the scale of the nutrient utilization. I.e. turning lights down low might have a lower intrinsic factor and thus, the rate is scaled down lower (but growth is still proportional to nutrients). I've factored out the intrinsic scale into a scale per unit volume so that it itself can be normalized by the volume that it is enacted over. The idea being that you have a tank with a particular lighting/spectrum/competition etc. and multiply this over some volume to account for effect size over an entire tank/fuge

The equation with dA/dt indicates the rate of algae growth with time. From above, it is proportional to the nutrients, but is scaled by the terms, p and V, which are constants. p can be modeled as being dependent on time (it definitely is) but this layer of complication is not necessary here because my assumption is that lighting/flow are the driving factors for most tanks and these are relatively constant (or can be averaged over some timespan)

It's important to note that the rate of algae growth in a display does NOT depend on the rate in the refugium. Therefore if you suddenly take out your fuge algae, the “instantaneous” rate of growth in your tank stays the same. But since these rates are 1st order (or higher) as the nutrients get taken in, the algae growth slows down unless more nutrients are added to refuel.

As for the total nutrients in the tank, I assume a constant influx of new nutrients (such as in the form of feedings). I.e. df/dt = a constant. The Nutrients in this model are always increasing (no water changes/removal of algae/no die off of algae). These things can be added in but again they don't change the trends and would make the notion more cumbersome.

With these assumptions, we just solve the equations for algae as a function of time for the display/fuge and the nutrients as a function of time

Since these are first order kinetics, the ratio of algae in each tank ends up being the ratio of their competitive advantages, though with higher order reactions the fractions would change somewhat

As part of my proof that algae at a distance can and does slow algae growth I show that as the comparative advantage becomes so large, algae at one location trends to 0

While the model is pretty robust to a lot of effects and trends that we will see in our tanks, I wouldn't read into the exact values of the numbers entered. If we wanted a more accurate model, to be used on a tank by tank basis, we'd need to characterize precise values of the intrinsic growth params (or actually just a good idea of the relative advantage, i.e. if we knew that the refugium was 120x better at growing algae per area than the DT). But we can use this model to predict how much the advantage needs to be to get a certain split of algae in the DT/fuge. Also we could get more accurate curves by knowing which nutrients in particular were rate limiting, and modeling the higher order reactions. It's actually feasible to do some home measurements of these without getting too complicated

I know this is a lot and I'm happy to keep discussing this! I find it really fun to talk models/theory, especially when they are useful. I'm also eager to contribute back to this community of reefers because I've learned so much on these forums.

Ugh, so complicated for such a simple thing... I do appreciate your technical input, but am not convinced it needs this much thought. I like practical solutions/ tangible answers.. Answer me this(please) , what's the mathematical explanation for this question/ scenario.. why is it that if I take a handful of gha from display and put it in the fuge it stays alive there and doesn't automatically regrow in display, but if I throw that handful in the trash it will regrow in the display everytime? There is already healthy gha in fuge and no other changes in system..

 

[VintageReefer]

It is because the amount in that handful is what’s necessary to absorb the excess nutrients in the system! By moving it to the sump it will absorb the excess from the water and grow in the new location.

Wen you throw it out, it is no longer absorbing the excess, and your display has a higher advantage as a growing algae - flow, lighting, whatever - your refugium setup isn’t more ideal to the algae. Your refugium keeps algae alive, but isn’t setup in a way to make it thrive.

That’s where the ATS comparative advantage comes into play. It’s powerful leds, often hitting 800-1000 par in the 660nm spectrum with flow conditions ideal for algae growth.

 

[mizimmer90]

Ugh, so complicated for such a simple thing... I do appreciate your technical input, but am not convinced it needs this much thought. I like practical solutions/ tangible answers.. Answer me this(please) , what's the mathematical explanation for this question/ scenario.. why is it that if I take a handful of gha from display and put it in the fuge it stays alive there and doesn't automatically regrow in display, but if I throw that handful in the trash it will regrow in the display everytime? There is already healthy gha in fuge and no other changes in system..

This is a brilliant response! The explanation from the model would be that if you throw the algae in the trash, you're changing the competitive landscape because you have less algae in the system to compete for nutrients. As the nutrients drop slower, it gives the DT time to regrow the gha.

Now, the reason I think this is brilliant is because I used the words "would be"... it would be if I included an extra term for the current algae amount in the rates! I.e. dA/dt is proportional to nutrients AND current A levels. I will include this when I get some free time and update the models to add to the complexity lol

I know it seems complicated but this is actually fairly simple as far as kinetic models go haha. I've helped model complicated enzymatic pathways with lots of different players where it's impossible to obtain a closed form solutions!! My current models are on structural dynamics of multiprotein systems and their conformational transitions between 1000s of states lol. This is fun stuff I can do in an evening!

Before the new model is updated though I can tell you ahead of time that it will end up making the competitive landscape significantly more pronounced!

 

[mizimmer90]

Nice! You got it!

It is because the amount in that handful is what’s necessary to absorb the excess nutrients in the system! By moving it to the sump it will absorb the excess from the water and grow in the new location.

Wen you throw it out, it is no longer absorbing the excess, and your display has a higher advantage as a growing algae - flow, lighting, whatever - your refugium setup isn’t more ideal to the algae. Your refugium keeps algae alive, but isn’t setup in a way to make it thrive.

That’s where the ATS comparative advantage comes into play. It’s powerful leds, often hitting 800-1000 par in the 660nm spectrum with flow conditions ideal for algae growth.

 

[Reefering1]

Nice! You got it!

Lol. I'll just smile and nod. But, if im understanding correctly, essentially you're concurring with vintage that my display out competes my fuge by design?

 

[Garf]

Ugh, so complicated for such a simple thing... I do appreciate your technical input, but am not convinced it needs this much thought. I like practical solutions/ tangible answers.. Answer me this(please) , what's the mathematical explanation for this question/ scenario.. why is it that if I take a handful of gha from display and put it in the fuge it stays alive there and doesn't automatically regrow in display, but if I throw that handful in the trash it will regrow in the display everytime? There is already healthy gha in fuge and no other changes in system..

Everyone is capable of cherrypicking, intentionally or not.

It is because the amount in that handful is what’s necessary to absorb the excess nutrients in the system! By moving it to the sump it will absorb the excess from the water and grow in the new location.

Wen you throw it out, it is no longer absorbing the excess, and your display has a higher advantage as a growing algae - flow, lighting, whatever - your refugium setup isn’t more ideal to the algae. Your refugium keeps algae alive, but isn’t setup in a way to make it thrive.

That’s where the ATS comparative advantage comes into play. It’s powerful leds, often hitting 800-1000 par in the 660nm spectrum with flow conditions ideal for algae growth.

Yeah, right.

This is a brilliant response! The explanation from the model would be that if you throw the algae in the trash, you're changing the competitive landscape because you have less algae in the system to compete for nutrients. As the nutrients drop slower, it gives the DT time to regrow the gha.

Now, the reason I think this is brilliant is because I used the words "would be"... it would be if I included an extra term for the current algae amount in the rates! I.e. dA/dt is proportional to nutrients AND current A levels. I will include this when I get some free time and update the models to add to the complexity lol

I know it seems complicated but this is actually fairly simple as far as kinetic models go haha. I've helped model complicated enzymatic pathways with lots of different players where it's impossible to obtain a closed form solutions!! My current models are on structural dynamics of multiprotein systems and their conformational transitions between 1000s of states lol. This is fun stuff I can do in an evening!

Before the new model is updated though I can tell you ahead of time that it will end up making the competitive landscape significantly more pronounced!

Algae are also limited by nutrient uptake limitations and do not scale up relative to nutrient density, in fact quite the opposite, for some nutrients.

 

[Reefering1]

Everyone is capable of cherrypicking, intentionally or not.

Yeah, right.

Algae are also limited by nutrient uptake limitations and do not scale up relative to nutrient density, in fact quite the opposite, for some nutrients.

Cherry picking what? I'm trying to understand all perspectives.. that's just a relative observation that I don't have a answer to why. What's your take/opinion?

 

[Reefering1]

Everyone is capable of cherrypicking, intentionally or not.

Yeah, right.

Algae are also limited by nutrient uptake limitations and do not scale up relative to nutrient density, in fact quite the opposite, for some nutrients.

Sorry these equations don't connect with what I see in my tank, I'm no scientist, just trying to keep a open mind. Vintages answer is easily relatable, is his your view also?

 

[mizimmer90]

Lol. I'll just smile and nod. But, if im understanding correctly, essentially you're concurring with vintage that my display out competes my fuge by design?

I'm not making any claims to anyone's particular tank or what should or shouldn't happen. But the equations detail how algae in the fuge/display would compete with one another and what their relative fractions would be given certain comparative advantages!

 

[mizimmer90]

Algae are also limited by nutrient uptake limitations and do not scale up relative to nutrient density, in fact quite the opposite, for some nutrients.

This is a good point! There are definitely some conditions where excess nutrients slow growth!

My model is under a rate-limited nutrient regeime, where the assumption is that there exists some nutrient that growth is limited by. I posted an article a ways back in this thread about iron being considered a limiting resource for algae growth in the oceans, where it's increase does cause large blooms in growth. My model is agnostic to "what" that nutrient is, but the N in my equations represents this nutrient.

 

[Garf]

Cherry picking what? I'm trying to understand all perspectives.. that's just a relative observation that I don't have a answer to why. What's your take/opinion?

Sometimes we believe we see a correlation between actions and results, that do not actually exist. This would call for an actual experiment. I think I get a red at every stop light, for example.