Brightness at the highest settings. works well for plants like Anubias Nanak growing without additional lighting and also seems bright enough for my reference Revain Sword. I use their 30 gallon clear acrylic Bitbon tank so I'm considering adding another to get enough light for the plants that need more light. I could probably put on 3 of these if needed. Timer function leave it on full brightness for 2 hours then switch to moonlight for 6 hours to see at night, overall for $25 they are great. I've spent over $200 on a t5 fluorescent system that worked fine in my 55 gallon corner tank, but I think I'll get the same results using 2 or 3 of these at a much lower cost.