...99% yours is fine, but you can't take confident action without some certainty about the most basic variable. Was thinking along with #scurvy as well. Phosphate could diminish corals, but running at 0 also invites dinos. They can be toxic. Also, if they're your major "algea," your CUC...
...the stand myself not Perfect but I'm no carpenter lol
I used a eshopps overflow down to a Trigger sapphire sump thanks to a great deal from #scurvy
I used a split return with valves and one way valve on each just in case the power goes out it won't siphon back into the sump
I'm using a...