Thanks. I'll leave the LEDs on 24/7 and watch what happens.
The water in this tank still has an odor, a lot like poop. So I cleaned the sponge again today and changed 3 gallons of water while syphoning out debris from the bottom. I did a good job of it. Most of the odor is gone, but not all. Tomorrow, if the odor remains and/or is worse than today, I plan to pull one of the drops and clean it thoroughly and the other one on Wednesday. Yes, I know this will set back the algae growth but if the odor is not coming from the sponge, it's coming from one or both drops. There's nothing else in the tank but the fish and a couple of apple snails. I clean debris from the bottom every day with a pipette, so there's nothing building up on the bottom. I'll do water changes to keep nutrients fairly low until the algae grows back.