It's NOT phosphate with the way those corals look I would say possible low Ca if you are using API and getting a reading of 450 you calcium could be as low as 380 but the high alk is more likly the problem.
The API phosphate test is almost useless in a SPS tank the lowest reading is .25 I would shoot for .06-.03
Definitely lower your alk to 7.5-8
I would invest in good test kits if you really want to buy something to help with color.
Salifert for Ca,ALk,MG
And Hanna phosphorous for phosphate
Also I'm will to bet adding a small amout of amino acids every day would help as well. Your corals look starved and burnt. Just my opinion but I have consistently good color and growth with the kits and parameters I've recommend.
The API phosphate test is almost useless in a SPS tank the lowest reading is .25 I would shoot for .06-.03
Definitely lower your alk to 7.5-8
I would invest in good test kits if you really want to buy something to help with color.
Salifert for Ca,ALk,MG
And Hanna phosphorous for phosphate
Also I'm will to bet adding a small amout of amino acids every day would help as well. Your corals look starved and burnt. Just my opinion but I have consistently good color and growth with the kits and parameters I've recommend.


