I have an RO/DI unit on which I bypassed the RO part to get just DI water for the tank (because of the 6x water waste with RO). I have a 180 on which I replace 3 gals a day due to evap. Plenty of algae (red, green, brown, black), so I plan to: 1) replace the DI filter and start using full RO/DI water, 2) Put the glass back on the top to limit evaporation, 3) start feeding half as much, 4) put sponge filters on the powerheads (and clean them 2x/wk), 5) blow the algae off the rocks and remove the algae carpet on the sand.
Obviously there are a multitude of reasons for algae, but I bought a phosphate test kit to check my water pre and post RO/DI to see what's up.
Jury's still out for me...