Are 0.0 phosphates always undesirable?

iko2thdk · Jul 31, 2020

My build is fairly simple. RSR350, live rock and sand, established about 18 months ago. LPS seems to do well. SPS not so much. Die back and shrinkage, not right away, but generally within months I seem to lose the SPS frags I put in. 2 AI Hydra 26s, contemplating T5s. Parameters:
pH 8.1
Alk 9.0 (Hanna)
Calc 490
Phos 0.0 (also Hanna)
Nitrates about 10.0 (API)

Lots of clean up crew, very little algae except on the glass, which waxes and wanes with the amount of feeding I'm doing. The fish are all happy, eating and growing. My anemone just split. Carbon in a reactor. Using about 7 tablespoons of GFO in a mesh bag in the sump.

Should I be dosing phosphates? Feed more? Discontinue GFO? (I had a wicked GHA outbreak a few months ago which vanished with a water change and add'l CUC. Obviously the tank runs ULN, but I'm disturbed that my corals have not been more prolific...

piranhaman00 · Jul 31, 2020

YankeeTankee · Jul 31, 2020

I'd slowly attempt to raise phos to at least 0.03

The last thing you want are dinos

Just go slow!

TexasReefer82 · Jul 31, 2020

Keep in mind that when we measure 0.0 phosphate what we're really saying is that the phosphate in our tank water is below the limit of detection of the gauge we're using to measure it.

Otherwise, 0.0 on a Hanna ULR Checker is a low phosphate number for a captive reef that doesn't receive the daily planktonic food the wild reef does.

I'd start feeding Reef Roids a couple times per week - your corals will love it and frankly I think of it as a phosphate supplement, haha. It'll raise phosphate for sure.

I'd lower your alk down to 7-7.5. Low nutrients and high alk don't mix - no one really knows why but it make SPS unhappy and often results in burnt tips.

Unless your water is yellow (and since the tank is new it's probably not yet) I'd stop the GAC. It can pull out dissolved organics that the corals use as food.

Successive algae blooms that wax and wane are all a normal part of the maturation of a new tank. You're not doing anything wrong if you have a hair algae bloom. Appropriate herbivores are an integral part of even wild reefs. If you can't grow algae in the tank you surely can't grow corals either.

Adamantium · Jul 31, 2020

I’m having the same exact issue. Nitrates ~10PPM, phosphates testing at 0.00 on Hanna LR.

I’d second the idea of dosing reef roids a few times per week. In my past experience, it shoots PO4 up, without impacting NO3 much.

Dr. Jim · Jul 31, 2020

Consider dosing with trisodium phosphate to get a more controlled increase. You can DIY or consider Brightwell's NeoPhos.

PatW · Jul 31, 2020

You want some phosphate. Corals need some phosphate and nitrate.

Now some of this has to do with your export system. I don’t know if GFO was your only system of removal or not. You want to be careful with it. It takes phosphates down really fast and that can starve your corals. I think GFO is kind of tricky to use in maintaining something like a stable level of phosphate.

I have used Chaeto in a refugium as a form of nutrient export. When I do this, I need to dose phosphate (trisodium phosphate) and nitrate.

The popular level is .03 ppm. You can dose phosphate to bring the numbers up. As stated above, Brightwell’s Neophos works well. Trisodium Phosphate works well and you can buy it as an analytical grade reagent fairly inexpensively. I put 2 tablespoons of crystals into a gallon of RODI for a stock solution. I teaspoon of this will bring up 100 gallons to a decent phosphate level.

In your case, I would not bother dosing right now. I would just let the phosphate levels come back up from feeding. You might get some Neophos and add a bit to get the phosphates just measurable with a Hanna ULR phosphorous detector.

Randy Holmes-Farley · Jul 31, 2020

iko2thdk said:
My build is fairly simple. RSR350, live rock and sand, established about 18 months ago. LPS seems to do well. SPS not so much. Die back and shrinkage, not right away, but generally within months I seem to lose the SPS frags I put in. 2 AI Hydra 26s, contemplating T5s. Parameters:
pH 8.1
Alk 9.0 (Hanna)
Calc 490
Phos 0.0 (also Hanna)
Nitrates about 10.0 (API)

Lots of clean up crew, very little algae except on the glass, which waxes and wanes with the amount of feeding I'm doing. The fish are all happy, eating and growing. My anemone just split. Carbon in a reactor. Using about 7 tablespoons of GFO in a mesh bag in the sump.

Should I be dosing phosphates? Feed more? Discontinue GFO? (I had a wicked GHA outbreak a few months ago which vanished with a water change and add'l CUC. Obviously the tank runs ULN, but I'm disturbed that my corals have not been more prolific...

Be careful with your significant figures and units of measure.

0.0 is not necessarily too low, since it presumably could be 0.04 ppm.

As to what you really mean, which Hanna?

Randy Holmes-Farley · Jul 31, 2020

Adamantium said:
I’m having the same exact issue. Nitrates ~10PPM, phosphates testing at 0.00 on Hanna LR.

I’d second the idea of dosing reef roids a few times per week. In my past experience, it shoots PO4 up, without impacting NO3 much.

Just as a clarification, the Hanna LR 713 does not really read low enough to say with certainty whether phosphate is too low.

It has an uncertainty as large as more folks target value (+/- 0.04 ppm).

iko2thdk · Aug 1, 2020

Randy Holmes-Farley said:
Be careful with your significant figures and units of measure.

0.0 is not necessarily too low, since it presumably could be 0.04 ppm.

As to what you really mean, which Hanna?

Thanks for the reply. I don't want to be one of those obsessive testers. But, since I have only enjoyed limited success is reefing, my thoughts turned to water parameters. I use the the Hanna Ultra Low Range Phosphate Checker with reagent #H1774-0. I was concerned about the same which is why I switched to the ULR. My LFS guy says feed more frozen food to the fish. Perhaps feed the corals reef roids? Ocean feast? IDK....