Sunshine State

Hello, I have been searching through information on this site and can't quite find the answer to my question. How high can phosphates be without harming fish? Is there a "don't go above" reading? I understand about the relationship to algae growth, can't quite come up with answers about are phosphates harmful to fish (or how much is harmful) Any help? Thanks.

Nate McFin

Per API phosphate test kit-
Phosphates are not harmful to fish.
http://aquariumpharm.com/Products/Pr...x?ProductID=76

sirdarksol

By the point the phosphorous is directly harmful to fish, you'll have much bigger problems than phosphorous.

The most obvious way phosphates can harm fish is by fueling algae (and cyanobacteria) growth.

Sunshine State

Thanks, I feel better now. About a week ago, I was told I should test for phosphates. So I bought an API phosphate test kit and did the test on my 75 gallon freshwater tank. The color of the water in the test was DARK. By comparing my test tube bottle to the color chart, I figure it is 5.0 maybe a little higher, but not quite as dark as 10. Anyway, I started reading all I could about phosphates, but never came across anything that specifically said what level of phosphates is acceptable. My water is crystal clear, fish are happy, healthy and thriving so I guess I can stop worrying about phosphates? Never had a problem with algae. Judith

Angela_96

I personally do not worry abotu phosphates in my FW tanks at all. In my salty tank I chedck them every now and then because they do feed the cyno, hair algae, etc.

sirdarksol

I don't either.
I'm aware that, if I'm having an algae bloom, I likely have an excess of phosphorous, but since nitrogen and light are usually the bigger culprits in FW setups, I concentrate on monitoring/adjusting those, and I've never had a problem.

Angela_96

Yeah, def everything else will be off first. I haven't had an aglae prob in my fw tanks since I got timers on them and 2 days out of the week is my "cloudy day" where no lights in the fw get turned on at all.