Can high Phosphates over 10ppm + Kill Fish?

[Bigzman]

Hello,

I helped my buddy with converting his 500+ gallon tank from FOWLR to Reef. He has had many fish death in the last 6 months. When he sold the remaining fish we measured parameters but this time we tested phosphates. API test so high that the dark blue maxed out the color card 10ppm and the salifert was worse maxing out the 3ppm max range. All other parameters was with in range. CA440, ALK 11, Nitrate .03, Mag 1400. Can Phosphates over 10pm cause fish health issue? Tank is now on 3rd week of running GFO and we have manged to get it down to 3ppm.

Thx

 

[saltyfilmfolks]

I’d wager the Po4 is not the problem it’s what ever the Po4 came in with.
Going from 10-3 just running gfo , it shouldn’t work like that.

 

[ckalupa]

Most people running saltwater fish-only dont even measure it and I have known plenty that are also pretty poor on performing water changes and have heavily-fed fish (like Lionfish) - I would guess their phos ranges are extremely high compared to what is acceptable in reef tanks.

 

[Randy Holmes-Farley Verified Community Expert]

I have no idea what level of phosphate harms fish, but I would guess that this is not the issue.