I have a 20 gallon long tank and am trying to figure out how much lighting I should have. I'm not using CO2 and the plants are dwarf sag, limnophila sessiliflora, dwarf sag.
The tank came with a 8W, 900 lumen LED light which is on for 10 hours/day - and I'm unsure whether this is enough? The lid has a second slot so I couldget a second light (they make a "plant" version which is also 8W LED but I think has more wavelengths that plants can use). So this would bring me up to 1,800 lumens.