My RO/DI unit is a BRS 4 stage value plus RO/DI unit-75 GPD. It is great for small tank. Although, depending on what tank size you have, bigger tanks should use at least 100 GPD filters. It is very easy to use, and creates enough water for my 20 gallon. It looks like a big advanced piece of technology, but it isn't. For tanks 50 gallons or lower, I would recommend this filter.