Why Phosphates are bad?

Randy Holmes-Farley · Feb 21, 2015

Yes, it is certainly an outlier from the normal advice.

UK_Pete · Feb 21, 2015

Is that tank not the one that its speculated has limiting iron?

glb · Feb 21, 2015

I use Hanna checker for phosphates and Red Sea for nitrates. I use the kit you have for my freshwater tanks and for them it's just fine. But for my saltwater, I found they weren't specific enough. Good luck!

Trey · Feb 21, 2015

great reads thanks Randy

bonz · Feb 22, 2015

If I have no algae should I not worry about the phosphates? I was thinking of adding phosguard.

Randy Holmes-Farley · Feb 23, 2015

I wouldn't add a binder to an existing happy reef tank unless you have reason to believe there is excess phosphate, either by algae or by a measurement.

glb · Feb 23, 2015

I just added Phosguard in mine because red algae took over. Following.

Randy Holmes-Farley · Feb 24, 2015

UK_Pete said:
Is that tank not the one that its speculated has limiting iron?

Yes.

tigerdragon · Feb 25, 2015

Randy Holmes-Farley said:
Yes.

What is meant by iron limiting?

hart24601 · Feb 25, 2015

That beautiful system that runs at a high phosphate level is interesting. I can tell when my GFO has reached capacity by a few corals that I have quickly (couple of days) turn brown. If I notice it they color back up pretty quickly after adding new media, but if I don't catch it for some time it can take quite a while to regain color. But I have noticed this many times of the past few years. I have a hard time thinking it's just coincidence because of the frequency and testing with hanna ultra low also shows phosphate rising. Any idea how he prevents browning out chemistry-wise?

Randy Holmes-Farley · Feb 25, 2015

tigerdragon said:
What is meant by iron limiting?

It means that certain organisms (such as algae) cannot grow despite everything else being plentiful, such as nitrate, phosphate, etc., because they do not have enough iron.

The analogy is limiting algae growth by having too little phosphate. In this case, you limit it by not having enough iron.

Randy Holmes-Farley · Feb 25, 2015

hart24601 said:
That beautiful system that runs at a high phosphate level is interesting. I can tell when my GFO has reached capacity by a few corals that I have quickly (couple of days) turn brown. If I notice it they color back up pretty quickly after adding new media, but if I don't catch it for some time it can take quite a while to regain color. But I have noticed this many times of the past few years. I have a hard time thinking it's just coincidence because of the frequency and testing with hanna ultra low also shows phosphate rising. Any idea how he prevents browning out chemistry-wise?

No, but the zoox may be limited by iron too.

tigerdragon · Feb 25, 2015

Randy Holmes-Farley said:
It means that certain organisms (such as algae) cannot grow despite everything else being plentiful, such as nitrate, phosphate, etc., because they do not have enough iron.

The analogy is limiting algae growth by having too little phosphate. In this case, you limit it by not having enough iron.

Ok that may be why i am seeing an inc in micro algaes since i started dosing red sea colors. May have to stop dosing them and see what happens

JSeward · Feb 25, 2015

Randy Holmes-Farley said:
It's not mine, it's Richard Ross's:

Reefs Magazine - Skeptical Reefkeeping IX: Test Kits, Chasing Numbers and Phosphate

[video=youtube;ZRIKW-9d2xI]https://www.youtube.com/watch?v=ZRIKW-9d2xI[/video]

UK_Pete · Feb 25, 2015

Limiting iron?

Yes :smile:

Thought so, I think you mention this tank in an article dont you Randy. It was very interesting to see a real world case of the theory that iron can limit algae (I realise its only a theory in that tank but it does seem quite likely). At least, something is obviously going on there with 2 ppm phosphate! One thing I took out of reading about that though was that iron is only required in very low quantities, far lower than phosphate IIRC, and I assumed that very few of us are going to be able to maintain that low level of iron, so despite getting quite excited at that when I first saw it, I realised that it didnt seem like a very practical alternative for most of us to target as a limiting nutrient compared to phosphate or nitrogen.

BTW on the subject of limiting nutrients, at reef levels of say the GBR at 3 ppb DIP, 3 ppb DOP, 1 ppb DIN and 70 ppb DON, do you think that corals and algaes are co limited by N and P or is one of them likely to be 'more limiting'? It seems quite complex because of the organic / inorganic bioavailability aspects, and P is required at lower levels than N but is present at more than 16 times lower levels etc. I was wondering in a reef tank which would be better to target as being the limiting nutrient, so allow the other nutrient in relative excess but strictly control the limiting one to a narrow range.

Randy Holmes-Farley · Feb 26, 2015

The thing about iron is that it is removed from the water quite quickly, so must tanks likely come to some sort if equilibrium between inputs and exports pretty quickly.

It may be a fine line to limit iron do algae doesn't thrive but not so much that creatures you want die.

Randy Holmes-Farley · Feb 26, 2015

As to corals, I don't recall any studies of which (if any) of these nutrients usually limits them in the ocean. For macroalgae and phytoplankton it can be N, P, or iron depending on the organism and the local conditions. Even in the same water it varies organism to organism.

For hard corals it might also be pH or alkalinity or light.

bonz · Feb 26, 2015

One of my corals were stning. I took it out to super glue and it was very brittle. The outer layer was flaking off.

https://www.reef2reef.com/forums/general-sps-discussion/192900-acropora-coral-problems.html

UK_Pete · Feb 27, 2015

Sorry Randy I just realised that the way I wrote my question made no sense (how to 'target' to limit coral growth, not what I meant). What I meant was to limit the zooxanthellae in the corals to increase color, and to limit the nuisance algae. So in a high nutrient environment corals would brown, and nuisance algae would thrive, what I mean was at the levels I posted above, IE on a real reef, which of them would be likely to be 'limiting' to the zoox and nuisance aglae. Is that still the same answer?

Randy Holmes-Farley · Feb 27, 2015

That is just what ULNS systems do: limit zoox levels to make corals brighter. Doing it with iron might not always work, however.

On a real reef, like Hawaii, some macroalgae are limited by N and some by P. phytoplankton is sometimes limited by iron. Beyond that, my knowledge about what is limited by what in the ocean runs out. It is not especially easy to test since it involves dosing in the ocean, or at least mimicking the ocean very well.