It is interesting to hear you mention that DOC's build up to a certain quantity and then level off. I have never read about this in marine aquariums. Is there something different about the FW environment that changes things?

I was just thinking about a system that could do smaller daily water changes using float valves.... maybe I will toy with that idea further. In the meantime my Python will carry me through lol.

I definitely don't mind doing water changes to correct/maintain things. I just like to always know why I am doing them

My tank is looking better than ever by the way. This coming week I am going to see if I can give it even more CO2, while still keeping the fishes happy.

Regards,