Dying SPS frags

[robbyville]

Yep, in my world NA is Nitrate, did I use the wrong abbreviation?

My Nitrates seem to hover around 10-25ppm, I'm not sure why I can never get them to 0, but I was told recently that my derasa clam needs some nitrates for survival. I'm not sure how to balance that though since I have always been told that corals need 0 Nitrates.

NB, all the frags and clams have been purchased through J&L, they seemed more than healthy under their lights but since I don't get down there often I don't get to cherry pick like some of you lucky people

I'll get that PH to you as soon as I get home, I'll try and snap a pic as well but the lights will have already gone off!

Best,

Rob