I have the larger CPR design like the two you were looking at, so I have a few first hand observations. First, these designs can really move a lot of water, much more than the U tube designs (which I have had a couple). With the CPR, I have tried attaching the air spill line to both a lifter pump, and not long after that to a maxijet 1200 powerhead. The problem with both of these is the same: the water going through the overflow is unfiltered, so you will get debris either plugging up the lifter pump (in very little time, even in spite of using the cheesy little mechanical filter they recommend), or else potentially after a longer period (for the power head in which case the airline tubing eventually gets a block, especially along the top surface of the overflow). When there is no obstruction, the maxijet can clear the entire air column out in a matter of seconds, very impressive (say after a power outage and assuming the siphon is broken). But if you use this, you must always do a periodic check to make sure an air column isn't forming along the top surface.
One other thing: they state that the flow rate through your system should closely match the max flow rate of the overflow or else problems may occur. Normally one thinks of the overflow not being able to handle the high throughput of a big pump, but in my case the opposite proves to also be problematic, which is if the pump is pushing too little in relation to the overflow's design capacity, more air bubbles will tend to be trapped in the overflow in a shorter amount of time. An LFS acquaintenance of mine said that he had the same problem, and after replacing his main sump pump with a more powerful pump he no longer has the air buildup problems which the air lifter and powerhead solutions protect against.
So, if you do go with this unit try to really match the pump to the overflow's rate carefully....not too big a pump, but then again not too big an overflow for the rate you anticipate either.
Scott
). It seems like it works really well.
