maintaining n & p for zoas?

[Baldy]

Hello,

In my current setup I'm running 2 phosban 150s. One with bioplastics, and the other with carbon and gfo. This has reduced the nitrates and phosphates in my tank to 0, even on the Hanna checker for phos.

Problem is that I'm trying to keep zoas, and can't seem to get them to survive. I have a bigger colony of emerald plays that have survived fine, some oreos that took off, then melted and died, and was left with 2 frags I had on a shelf. One survived melting barely and is still barely hanging on, and the other had half covered its frag rock. I moved the latter down and glued it to the live rock, and its melting now too. I thought it was hermits picking at them before so I've pulled a ton of them out, but it seems to not be helping

Should I be removing some of the bioplastics and gfo to try and maintain a low level of n & p?