CPR overflows rely on a powerhead to keep the air out of the siphon. This doesn't mean the water will hit the floor if the PH
quits though. You'll need a PH
to attach to the air line fitting on the overflow tube. I would suggest at least a Maxi Jet 900. The air line runs from the overflow tube to the venturi attachment on the PH
. The idea is that the suction from the venturi will clear any air bubbles that find their way into the tube. A strong PH
will even restart the siphon by itself. Personally, I like the old U tube overflows. I have had good service from them. You'll want to make sure that the air line going to the PH
is submerged even when the pump is shut off and the water level in the main tank drops. One thing to note: if the air line ever comes off, the siphon will break and the tank will overflow.