My 10m IC has a relatively small inner diameter of 6.5mm, about 1/4". I'm looking at aquarium pumps to pump ice water through it for the late chill when the 31C tap water just isn't cutting it. Any suggestions on flow rate for that size of IC or the best way to find my optimal flow rate? I suppose I could hook it up to the sink for a couple minutes and measure how much water it's using, but I'd prefer not to waste that much water if I don't have to.