There is not one that small I know of. You can build one with a slump switch and an mag drive pump.

Are you trying to build a control bucket for an ebb & grow system?

They use electric float switches 2 of them and 2 pump motors one is the 55 gallon drum and one in the control bucket.
Zandor Reviewed by Zandor on . C02 cooling effect on grow closet Would a steady flow of c02 from a large tank during light hours cool down a small grow room about 15 square ft enough that I could bring a 400 watt hps closer to the plants? Runester Rating: 5