here is the one i use http://www.marinedepot.com/ps_ViewIt...&option1=PF601
I got it from kingfish aquariums in austin.It is a very efficient unit. fluidised, bayonett top for easy loading. This unit doesnt really need a ph controller, but there is a port for one.A timer and a elec co2 solenoid is all you need. I run co2 to mine less than 3 hrs a day. I hear the aquabee pumps croak after awhile but mine has been going for quite awhile.