[untamed]

Originally Posted by Sebae again

The Aqualifter starts the siphon....

Originally Posted by fkshiu

The Lifereef is a u-tube style overflow that doesn't require a separate pump to maintain a siphon unlike the CPR. It's a malfunctioning pump that cause most CPR failures....

Statements like that lead to the common misconception that the CPR overflows REQUIRE that pump in order to restart after power failure. They should NOT require any kind of pump to restart after power failure. They are just like every other good siphon in that they have water collection boxes on either side of the siphon to ensure it restarts properly. Without those boxes, no siphon restarts automatically.

The pumps are there as a backup to ensure the siphon never collects air in the siphon. It is a fair statement to say that the rectangular shape of the CPR siphons may create a situation where more air might collect in the siphon, but I believe that all siphons have the potential to collect air bubbles that could cause siphon failure at any time..not only on restart.

It would not matter what kind of siphon I was operating, I would want some sort of pump pulling air out of the top of the siphon at all times. It is just safer.

I ran a CPR siphon for about 6 years. I used a RIO600 RVT for air removal and the system was very reliable. The only maintenance I did was to periodically ensure that the air line wasn't clogged.

If you ever drain the siphon collection boxes, then starting the siphon is a lot easier with some sort of pump helping you out. Otherwise, you have to stick a flexible tube up there and suck the air out manually.

The things that I did NOT like:
1) the actual siphon portion of the CPR is black so that algae won't grow in it. Yes, but I would feel better if I could see inside to know that the siphon was running properly.
2) Impossible to clean or disassemble. If anything got in there, you can't get it out. A removable "U-tube" would be much easier to deal with.
3) Siphons don't like when you jam your arm into the tank and cause rapid changes to water level. That's when floods happened to me.

I would never return to a siphon based system myself.