Super high phosphate

[GiannisK]

Hello all, I’m having a problem with phosphate in my aquarium and I’m really stumped. It’s a 20 gallon that’s been running for 5 months with a firefish, pair of clowns, starry blenny, and some inverts.

Measurements taken two days ago, which was 1 day after a 25% water change:
Nitrate: 10
Phosphate: 0.50
I also tested the phosphate again today, and it is now at 0.66. I was running fluval clearmax which is basically GFO I think but either it’s not doing anything or my phosphate is somehow rising faster than it’s being depleted.

It’s only a 20 gallon so I suppose some dwarf snails could have died and are buried in the sand but not anything bigger. I’ve been feeding TDO pellets exclusively lately, maybe it’s just too many of them I guess. But I’m really shocked at the imbalance, I mean my nitrate isn’t that high. I have been doing about 25% water changes every two weeks on average.

The thing is, up to mid January, my phosphate was testing at 0!! 0.66 is just shockingly high too me. I’m using the Hanna Phosphate (not ULR). For what it’s worth I also checked with the API phosphate and it matched.

I don’t make my own RODI water, I buy from a local store. But if their water was the problem I shouldn't be seeing it rapidly rising, should I?

I have a xenia, a galaxea, a chalice, a mushroom, a digitata , and two RBTAs (recently split). They’re all doing better than ever, far as I can tell. I don’t have any algae issues other than some growing on the glass quite slowly, and my tank is also now growing coralline.

Is there anything I can do? I’ve been replacing the GFO but it’s not doing anything. I was thinking of stopping all feeding for 2-3 days and see if the rise halts.

I would greatly appreciate any thoughts.

 

[coralboi56]

Dead animals wouldn/t increase phosphate. It'd more likely increase nitrate.

I would add official GFO or SeaChem PhosBond. And switch it out every few days. My phosphate went from .94 last week to .02 today after i kept up what the heck changing out PhosBond

 

[Randy Holmes-Farley]

There's a fair amount of debate on what the impacts are of elevated phosphate. There are great reef tanks with far higher levels than 0.5 ppm, so I'd wary of taking drastic action.

That said, if you still want to lower it, GFO is a fine but expensive way to go.

 

[GiannisK]

Dead animals wouldn/t increase phosphate. It'd more likely increase nitrate.

I would add official GFO or SeaChem PhosBond. And switch it out every few days. My phosphate went from .94 last week to .02 today after i kept up what the heck changing out PhosBond

There's a fair amount of debate on what the impacts are of elevated phosphate. There are great reef tanks with far higher levels than 0.5 ppm, so I'd wary of taking drastic action.

That said, if you still want to lower it, GFO is a fine but expensive way to go.

Thank you both for your replies. I don’t have PhosBond but was given a bucket’s worth of PhosGuard for free so I’m going to use that. Seachem claims it’s just a lower capacity version.

I’m more concerned with it rapidly rising than it being so high to be honest.

How quickly does GFO work? In other words, how long do I wait to test the water after I put it in?

 

[GiannisK]

I saw another post claiming dry rock absorbs phosphate initially. Could that be the reason I saw a sudden spike from 0 after a while? I did start with dry.

 

[Reef.]

How are you using gfo.? If in a bag its going to be not very efficient, reactor would be better, with a high po4 the gfo will exhaust fast if you have it working correctly, or not very fast at all if not, you will need to change it often.

Sounds to me it could be your water, if the reading was low a month ago and now its high, if you are not feeding coral food then that would be my guess.

I would carry on feeding as 3 days of not feeding is not fixing this, I would move to a good mix of frozen foods if you use pellets.

 

[Randy Holmes-Farley]

Thank you both for your replies. I don’t have PhosBond but was given a bucket’s worth of PhosGuard for free so I’m going to use that. Seachem claims it’s just a lower capacity version.

I’m more concerned with it rapidly rising than it being so high to be honest.

How quickly does GFO work? In other words, how long do I wait to test the water after I put it in?

All these binders work very fast in the sense of uptake and depletion when flow through them is good and levels are high (less than a day to depletion of the binder capacity), but the water levels can rapidly bounce back when phosphate desorbs from rock and sand, and the entire process to strip that out can take a long time.

 

[GiannisK]

I dont know anything about reactors and don’t have a sump so I don’t think I want to go down that route.

All these binders work very fast in the sense of uptake and depletion when flow through them is good and levels are high (less than a day to depletion of the binder capacity), but the water levels can rapidly bounce back when phosphate desorbs from rock and sand, and the entire process to strip that out can take a long time.

What I don’t understand this, why would the rock and sand absorb all the phosphate, then leech it all out? If it’s a matter of diffusion, I wouldn’t think I’d have 0 phosphates in the water while it was absorbing.

 

[GiannisK]

I have been using an HOB for this sort of media stuff. 250 gph.

 

[fishyjoes]

I dont know anything about reactors

Reactor is just a fancy name for a container that you pump water through to force it to come in contact with whatever media you put inside.

 

[Reef.]

I doubt very much your po4 was ever zero.

 

[Reef.]

I have been using an HOB for this sort of media stuff. 250 gph.

Your hob works the same as a reactor.

 

[GiannisK]

I doubt very much your po4 was ever zero.

I don’t have the ULR so it’s possible but it was undetectable with the LR every time I tested, about 10 or 20 times since getting the tester.

 

[Reef.]

I don’t have the ULR so it’s possible but it was undetectable with the LR every time I tested, about 10 or 20 times since getting the tester.

Have you tried testing the fresh salt water?

 

[GiannisK]

Have you tried testing the fresh salt water?

I will do that next just to be safe.

 

[exnisstech]

My most succesful tank, a mixed reef thrives with PO4 at 0.5 and a bit higher at times.

 

[Randy Holmes-Farley]

I dont know anything about reactors and don’t have a sump so I don’t think I want to go down that route.


What I don’t understand this, why would the rock and sand absorb all the phosphate, then leech it all out? If it’s a matter of diffusion, I wouldn’t think I’d have 0 phosphates in the water while it was absorbing.

It's an on/off equilibrium.

The higher the amount in the water, the more driving force for more to bind.

The more on the surface, the more driving force for more to desorb.

At any given phosphate concentration in the water, there is an equilibrium amount that will bind.
Higher concentration in the water means a higher equilibrium amount on the surfaces.

Thus, trying to raise or lower it meets resistance as more binds or more desorbs to reach a new equilibrium.

Same is true for most any material binding to most any other material (phosphate on GFO, simple organics on GAC, etc.)

 

[Randy Holmes-Farley]

My most succesful tank, a mixed reef thrives with PO4 at 0.5 and a bit higher at times.

It may thrive at 0.5 ppm, but they also thrive at 0.05 ppm.

 

[exnisstech]

It may thrive at 0.5 ppm, but they also thrive at 0.05 ppm.

That was just my way of saying 0.5 isn't super high phosphate IMO

 

[Randy Holmes-Farley]

That was just my way of saying 0.5 isn't super high phosphate IMO

Oh, OK, I thought it was a recommended value.