Sponges are the best natural filtration, hence the cryptic fuge. The two stage fuge sounds good.

Are you still considering the Algae Waterfall Scrubber? I was very happy with mine as I had almost completely eliminated the Asparagasum algae that had plagued my last system before I sold it.

This natural filtration takes time to develop, especially the sponges. Don’t be lured into the latest fad in water quality or ionic balance maintenance. Too many people get upset at the first sign of hair algae or cyano, rush out and purchase the latest snake oil or hop on the latest band wagon concept on the internet aimed at maintaining a healthy aquarium.

Most systems take a few months for the filtering life forms to reach equilibrium with changes to the system. e.g. new system, additional fish load, increased feeding, etc. With patience you are on your way to a system that will find its equilibrium and ionic balance.

As far as pH, most people don’t worry about night / day cycles. As long as the Alkalinity is high, the pH will be fine. Especially now that we have good flow and O2, CO2 exchange in our displays.

18 hours is a good length of time to light Cheatomorpha, but running the lights with the main lighting cycle works very well. RDP does help a little bit if Alk is not maintained, but many households are not conducive to the evening lights.