My moon lights are bright enough to concern me, too. I decided to have my timer keep them on for only about 4 hours during the night cycle. That way I can view the tank for a while after the lights are out but when I sleep, the plants and fish get to sleep in real darkness. I have heard of people having issues with really bright moon lights. The ones I had before my new ones were pure blue and really really dim. They stayed on all night and were fine. Probably comes down to how bright your LEDs are. If you think they might barely keep java moss alive all on their own shutting them off for at least 6 hours during the night is probably a good idea.