nitrate/phoshate problems

[sparkee61]

I've been having difficulty to the past 6 months on reducing nitrates and phosphates in my 210 saltwater tank. I've tried about everything: weekly 30 gal water changes, reduced feeding, GFO/carbon reactor, clean out sump, NoPox. RO water is at 0. Fish are fine, but corals are having a tough time. Any advice would be appreciated.
Salinity01.025 Ph- 8.2 Ammonia-0 nitrites- 0 Nitrates- 40 Phosphates- 5
Calcium- 440 Alkalinity- 8

 

[Sniperhank]

Though those nitrates aren't super high, the phosphates are.
What are you using to test your phosphates? Not all phosphate tests are created equal.
Are your water changes being done with ro/di water? You could just be putting it back in what you are trying to take out if not.

 

[sparkee61]

Yes, water changes are done with RO water which I test once filtered. I'm using API marine test

 

[Sniperhank]

Don't trust that API phosphate test kit. They are junk. API kits aren't for much more than cycling.

 

[Caliban07]

Don't trust that API phosphate test kit. They are junk. API kits aren't for much more than cycling.

This is 100% true

 

[sparkee61]

What test kits do you suggest?

 

[Sniperhank]

I'm a fan of hanna checkers and red sea test kits.