Hey Eric, this is what I suspected! I did mess with my nopox recently and probably dumped more in than I wanted while trying to prime the doser after redoing some lines. I'll wait a few days and if it gets too much, I'll drop the amount.The white on the algae that you're seeing isn't really due to the lack of iron, but rather from the bacteria activity. As noted above, NoPox is basically just carbon dosing (for bacteria). You can try dropping down your NoPox dosage slightly and it should go away.
Is rubble the ideal media? That sounds like a good idea.One tip on carbon dosing:
I put some rubble in the skimmer section, and carbon dose there.
It seems that more bacteria grows there, and as it dies and falls off, it gets immediate sucked up by the skimmer.
That was based on advice read online, and it did seem to work a bit better for me.