Ever had this weird phosphate problem?

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Steve1500

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I have 180 DT, w a 36G sump. Recently, I checked my phosphates with a Hanna checker (Low range, model 713). Results were .19-.25 over a course of 4-5 days. I did multiple water changes totaling about 60-70G. This did not make a dent in the phosphate levels. Other than a little cyano, which is normal in my tank, everything seems to be doing ok. Maybe it's because .23-.25 is not that big a deal. Tank is 2 years old. So.....


Out of curiosity, I checked my tap and RODI and both came out 0.0.

Then I checked out my freshly made SW in my brute bin and it was between .3 and .4 on a few different tests!

Went back and rechecked everything...Nitrates at 5-8 ppm, pH at 7.9-8.0, salt at about 1.025-1.026, all other parameters are stable.

So, my first assumption was that the hanna checker or the reagent were bad. But what confuses me is the RODI and tap are checking right (0.0).....Before I add the salt, I test the RODI. The problem arises after I add the salt to the bin.

My next assumption is that my salt (Brightwell NeoMarine) is bad (brand new bucket). Has anybody ever had high phosphates due to the salt?

BTW, my chaeto started dying a few months ago but it's out of stock everywhere. I feed 3 times a day but not heavy (20 fish/lots of coral). I also turned up my skimmer.

I have ordered more salt, more reagent and a Hanna checker phosphate calibration kit to rule some things out but this is driving me nuts. I also ordered some Brightwell phosphate remover in case the problem is really in my DT.

Thoughts?
 
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Randy Holmes-Farley

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I expect the salt mix test is an error somehow.

FWIW, water changes are not a good way to reduce phosphate as there is so much bound to rock and sand that will come off after a water change that even a 100% change might only cause a small drop.
 

Super Fly

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I expect the salt mix test is an error somehow.

FWIW, water changes are not a good way to reduce phosphate as there is so much bound to rock and sand that will come off after a water change that even a 100% change might only cause a small drop.
Curious, if this is the case, what would be the best way to reduce PO4?
 

Randy Holmes-Farley

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Curious, if this is the case, what would be the best way to reduce PO4?

Something that consumes it in the tank, like macroalgae or a phosphate binder such as GFO. :)
 
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Steve1500

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Curious, if this is the case, what would be the best way to reduce PO4?
I expect the salt mix test is an error somehow.

FWIW, water changes are not a good way to reduce phosphate as there is so much bound to rock and sand that will come off after a water change that even a 100% change might only cause a small drop.
Just tested my RODI bin and it’s reading 0.0. Same test process as always. Will retest sw bin again
 
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