Well I have a 125g and my plants are growing just fine. I believe my tank is 23" tall. You just need to make sure you get low light plants. There are advantages and disadvantages to all light fixtures in my opinion. These just suit me for what I'm trying to accomplish which is, less energy consumption, not buying bulbs every year, save money, these don't heat the water at all either, light spectrum doesn't change. Doesn't everything I need it to do =)