Phosphate won't come down

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HackBetty

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I've done a ton of research, but can't seem to get my phosphate down. It's currently at 0.46, yes you read that right.

What I've tried:
- Seachem PhosBond (dropped from 0.8 to 0.5ish for 2 days then starts climbing again)
- RedSea Algae Management NO3:PO4-X (lowered nitrates but not phosphates)
- Rowa phos (currently in the tank. Seeing to hold steady but not lower)

I feed heavy and dose with NeoNitro to keep nitrates from bottoming out. Also dosing with Reefcode B to keep alk stable. Chaetogro once a week ish.

Occupants:
2 clown fish
1 two-spotted tang
1 CBS
10 nassarius
2 ceriths
1 astrea (2 died a few weeks ago)
1 Mexican turbo snail
Duncan
Branching hammer
GSP
Montipora
Candy cane coral
Plate coral
Chaeto
(Had a birds nest that died when the calcium bottomed out in March)
Couple bristle worms (these things freak me out)
Copepods
Pineapple sponge infestation that started a couple weeks ago

Running
Filter sock (change every 3 days)
Rowa phos
Purigen (which I'm not sure is doing anything as it's growing algae but not turning brown)

Parameters in pictures.

I'm at a loss... please help.

20250423_213031.jpg 20250423_213047.jpg 20250423_213055.jpg
 
I’m using Phosguard to lower mine for now (went from 0,32 ppm to 0,16 ppm in about 12 days) and bought an algae turf scrubber that will hopefully bring them down more, along with nitrates. If it works I won’t have to use anything else.
 
So the P source is the heavy feeding…

Do you have issues you associate with your current phosphate level? It’s higher than I target but people have nice tanks with higher phosphate.

GFO and rowaphos remove phospate. If you are not getting the reduction you want then use more or change more frequently. But go SLOW. Lots of negative impacts to corals when phosphate is reduced too quickly.
 
0.46 ppm phosphate may sound scary, but it’s not an emergency. Some great tanks have much higher phosphate.

That said, there are many good ways to reduce it, including GFO, aluminum oxide, and lanthanum (tang risks, however).

Organic carbon dosing such as NOPOX is not generally a great plan for phosphate.
 
You don’t have enough corals to consume the heavy nutrient. Cut back on the feeding and continue to run Rowaphos. Change the media every week.
 
You don’t have enough corals to consume the heavy nutrient. Cut back on the feeding and continue to run Rowaphos. Change the media every week.

You think that he should cut back feeding despite the fact that nitrate bottoms out when not dosing nitrate?
 
You think that he should cut back feeding despite the fact that nitrate bottoms out when not dosing nitrate?
I was curious about that too.

To clarify, I feed a few PE pellets to the clown fish, a pinch or two of those for the tang as they seem thebe his favorite, a couple algae pellets for the tang, half a piece of seaweed that either the tang or turbo eats, and then either a 1/2 or whole cube of mysis shrimp OR 2 pumps of phytoplankton. This is once a day in the evening.
 
Idk, that actually sounds to me like a lot of food daily for three fish and very little coral. At the same time, I wouldn’t really worry about that phosphate level. Your tank looks clean. How big and how old is it? I dose ammonium chloride as needed to keep my nitrates between 5-10 ppm.
 
So just to clarify my opinion , I would not cut back food. :)
I find feeding is fairly ineffective at boosting nitrate relative to phosphate. Some changes in foods can help, but many tanks seem to have immense capacity to process N relative to P. If it were my tank, I would cut back feeding if I wanted to reduce phospate.
 
The only way I was able to keep phosphate in check long term was to learn that some foods are much higher in phosphate than others, and adjust my feeding to mostly the low phosphate foods. I still use the higher phosphate foods, but not as often.

This article from the reef chemistry forum has good phosphate in general
https://www.reef2reef.com/ams/phosphate-in-the-reef-aquarium.9/
It links to another Randy Holmes-Farley article (that I can't get to load right now) that goes into detail about the phosphate content in various foods
http://www.advancedaquarist.com/2012/3/chemistry
 
If they are feeding too much, I would also reduce it and simply dose nitrate or ammonium — no point in overfeeding to only raise nitrate.

Whether they continue overfeeding or not, using a phosphate remover is the only way to meaningfully bring it back down.
 
Well, as the chart says, looks like it was up to .9, so it has gone down.

I am currently dosing lanthanum chloride in to a 1 micron filter sock to lower mine, which who knows how high it is, it blinks .9 on my hanna. FWIW, my tank seems fine except I cannot officially beat dinos, but I am limiting them with almost daily maintenance.
 
+1 on Phosphate RX. I've been battling high PO4 for years. My tank is 5 years old. I just lowered my tank from 1.32 ppm to 0.08 overnight. I did 125 drops at night and another 125 drops in the morning.

Keep in mind the phosphates are probably bound in your rocks and substrate so more po4 might leech out now that the water is not saturated. I've been doing about 10 drops a day to keep my PO4 at 0.16-.20

Once I notice that the PO4 isn't rising anymore, I can switch back to GFO/Rowaphos to keep it down.

I have lots of tangs in my tank and had zero casualties. No signs of stress on the fish nor the corals. (SPS dominant)
 
I use rowa in a reactor and it works flawlessly. Back when I would run it the media bag they provide it didn’t do much
 
0.46 ppm phosphate may sound scary, but it’s not an emergency. Some great tanks have much higher phosphate.

That said, there are many good ways to reduce it, including GFO, aluminum oxide, and lanthanum (tang risks, however).

Organic carbon dosing such as NOPOX is not generally a great plan for phosphate.
Here is a section of my LPS dominant 120. PO is a constant 1.0
 

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