I think it's meant for a four feet tank. I used it on a nanocube and it was way over powered. Do check with other sources though. I am not an expert on such matters.
I found this online
'1/10 Hp inline chiller recommended for aquariums up to 130 gallons'. (Sizing Guide). Features built in temperature controller with digital display, titanium heat exchanger, black ABS cover, and a 2-year warranty. Unit produces some of the lowest noise and vibration levels of any chiller on the market. Recommended Flow Rate: 240 gph. Input/Output: 1/2", 5/8", 3/4" INS (Hose Barb). Using either an existing pump or an additional pump, water is circulated through the chiller, cooled, and returned to the aquarium or filter system. All models are safe for use in either salt or fresh water.
A chart can be found in the link http://www.vividaquariums.com/10Expand.asp...tCode=04-1512-1