Question about phosphates and test

[Mattj815]

So about 2 months ago I had a bunch of GHA. I was getting 0 on api po4 test kit. Now ive always heard that the test may be inaccaurate bc the gha is taking all the po4 in before the test will read it.

So I started running gfo in a reactor about a month and a half ago and my tank is looking much better. The bulk of gha is gone aside from a few spots.

I upgraded my test kit to the red sea po4. Just tested and got 0. I still do have some algae especially on the backwall and sand. But not too bad. Now, did I just do such an awesome job getting my numbers down or is it still a false reading?

Nitrates are about 1.5ppm on redsea

Any ideas?

 

[ndrwater]

IMO, any of the titration phosphate kits aren't all that accurate. Although GFO is very good at stripping phosphate from the water, I would guess there is at least some detectable amount.
I would suggest the Hanna Checkers. They work, and seem to be much more accurate than any titration tests.

 

[mcarroll]

Fighting algae via nutrient export doesn't work.

At least not like that/not like we'd like it to.

That's the simplest way to explain it.

Bear with me on the non-simple explanation....

Your test kit doesn't lie, it just can't tell the whole story. It has limits that you need to be aware of. Limits in accuracy, precision and scope.

These limits don't make the test any more useless...every kit has limits.

The only time these limits are a problem is when we assume the test IS telling the whole story and then base our actions on that partial info.

With that in mind, your test measurements, which are specific for PO4, are largely done to allow us to guage overall nutrient levels in the system.

If you use chemical media (eg GFO) to tweak one nutrient, you haven't really changed anything in the overall picture nor with overall nutrient levels, right?

You just used a chemistry hack to make your already-limited test kit read the number you wanted to see.

A good trick, but the algae aren't always impressed.

Algae (considering them all en masse) could be getting access to phosphate from any exposed rock surfaces (which binds phosphate almost exactly like GFO, and which is where pest algae often grows until excluded by coraline algae/other), or by using other forms of phosphate that other organisms can't, or by simply having abilities to gather phosphate down to super-low levels, below where corals or "normal algae" could access it. Some algae can even make their own nitrogen.

So in many or even most situations, nutrient limitation vs algae is a losing prospect. You have to get lucky to "win".

Going forward, you should try thinking about "progression" rather than "limitation".

You want to get all your rock through the cyano>green algae>coraline|coral cycle to that end phase.

To get there, your system will need A LOT of nitrates and phosphates. Don't make your tank's progression compete with a media reactor or an algae scrubber or anything else, IMO, until the main display is in full swing and past its problems.

You'll have to grow some algae, clean some algae by hand, and beef up your cleanup crew along the way....but that's the way to get where you're going. (A stable system.)

Can you post a pic of the tank with flow off? (Usually easier to see algae in pics without flow.)

 

[Mattj815]

Fighting algae via nutrient export doesn't work.

At least not like that/not like we'd like it to.

That's the simplest way to explain it.

Bear with me on the non-simple explanation....

Your test kit doesn't lie, it just can't tell the whole story. It has limits that you need to be aware of. Limits in accuracy, precision and scope.

These limits don't make the test any more useless...every kit has limits.

The only time these limits are a problem is when we assume the test IS telling the whole story and then base our actions on that partial info.

With that in mind, your test measurements, which are specific for PO4, are largely done to allow us to guage overall nutrient levels in the system.

If you use chemical media (eg GFO) to tweak one nutrient, you haven't really changed anything in the overall picture nor with overall nutrient levels, right?

You just used a chemistry hack to make your already-limited test kit read the number you wanted to see.

A good trick, but the algae aren't always impressed.

Algae (considering them all en masse) could be getting access to phosphate from any exposed rock surfaces (which binds phosphate almost exactly like GFO, and which is where pest algae often grows until excluded by coraline algae/other), or by using other forms of phosphate that other organisms can't, or by simply having abilities to gather phosphate down to super-low levels, below where corals or "normal algae" could access it. Some algae can even make their own nitrogen.

So in many or even most situations, nutrient limitation vs algae is a losing prospect. You have to get lucky to "win".

Going forward, you should try thinking about "progression" rather than "limitation".

You want to get all your rock through the cyano>green algae>coraline|coral cycle to that end phase.

To get there, your system will need A LOT of nitrates and phosphates. Don't make your tank's progression compete with a media reactor or an algae scrubber or anything else, IMO, until the main display is in full swing and past its problems.

You'll have to grow some algae, clean some algae by hand, and beef up your cleanup crew along the way....but that's the way to get where you're going. (A stable system.)

Can you post a pic of the tank with flow off? (Usually easier to see algae in pics without flow.)

So yes I used gfo to tweak one nutrient. But combined with other things we tweak a lot. Po4, skimmers for other things, carbon for others etc. And water changes so all that together has gotta be doing something good right?

I get the cycle you speak of and waiting out a mature system. But for someone like me who has very little patience the gfo solution is making look at my tank more enjoyable.

This hobby is definitely making me a more patient person.

Here are some pics if that helps


And ndr thank you too, I learned a new word today

 

[biophilia]

What sort of cleanup crew do you have? I'd start there. For that tank, maybe 7-10 snails of various species (mostly Trochus if you can find them!) and 7-10 hermits and you won't have to worry about algae ever again. Adding an algae-eating fish might be a good option too. In wild reefs, 80-100% of algal biomass that grows each day is consumed by the herbivores in a period of 8-12 hours. So there's a ton of it, but it's consumed as quickly as it grows. I think that all of the images of colorful, coral-dominated, algae-free reefs has led to a perception that algae is something that should not exist in our reef tanks -- when it reality it's much easier to focus on adding an appropriate number of herbivores to regulate it than to fight with water chemistry to keep it dormant.

 

[Mattj815]

What sort of cleanup crew do you have? I'd start there. For that tank, maybe 7-10 snails of various species (mostly Trochus if you can find them!) and 7-10 hermits and you won't have to worry about algae ever again. Adding an algae-eating fish might be a good option too. In wild reefs, 80-100% of algal biomass per day is consumed by the herbivores in a period of 8-12 hours. So there's a ton of it, but it's consumed as quickly as it grows. I think that all of the images of colorful, coral-dominated, algae-free reefs has led to a perception that algae is something that should not exist in our reef tanks -- when it reality it's much easier to focus on adding an appropriate number of herbivores to regulate it than to fight with water chemistry to keep it dormant.

Right now i have about 5 turban snails. 2 hermits and 2 nassarius if the hermits left them alone. Also have 1 emerald crab and a tuxedo urchin.

Any ideas for a fish? I was planning on more colorful swimming fish in here and being only 40 gals im limited in stocking.

 

[cracker]

Honestly Matt the tank looks pretty good. That's not a bunch of algae .

 

[biophilia]

With a 40 gallon, definitely look more towards snails/hermits to control algae, but a tailspot blenny would be a good choice as far as fish go. Not super colorful, though, unfortunately. Mostly, I'd say consider adding a few more hermits and the next time you do a water change, scrape as much of that algae on the back wall out as you can and you should be good to go. The minor algae issues should fix themselves in time if you keep up on good tank husbandry.

PO4 test can be pretty inaccurate. Elos Professional and the Hanna low range checker are probaby the only ones that are worth a grain of salt, but IMO it's easier to just use presence of algae on the glass as an indicator of how much phosphate your tank actually has.

 

[Mattj815]

Honestly Matt the tank looks pretty good. That's not a bunch of algae .

Thanks. Yeah im happy with it and know I still have a while to go before its stable and "mature".

Just didnt know if I was missing something with the test reading 0. Hanna kits are going on my list to Santa