Lowest! I did though go extra on the pump. 1,200 gph. Other than that,its basic fish keeping and yes,window light is most of the lumens.
This is A.r. rosaefolia . Dennis Wong rates it as easiest of them all to grow and so far he's been right on. No Co2 and even my window is not like some ADA Solar on for 7 or 8 hours...it isn't until the afternoon that it gets intense from the sun.
But,sunlight is just the worst or best,on making algae in the tank. I tell you,make sure you keep the organics low or every form of algae will show up. Also,less fish is the way to go..small fish. Rainbows are not small fish.
Go small fish and window light becomes much more workable.