Get a utube, lifereef is the best, hurrican's and amiracles are much less and good utube's, there just not as thick acrylic as a lifereef and don't do as much gph stock either, but half or 1/3 the price........nothin an extra 5dollar utube won't fix!
I had a CPR. Never had a problem with it but I would NOT recommend it. The build in siphon is near impossible to clean. You can't get a sponge or anything else into the inner portions. Short of removing it and soaking the whole thing in bleach, I dont know how it could be cleaned if needed. Also, it relies on a constant removal of air from the siphon by using a pump or powerhead air intake. Air will build up and you lose siphon and overflow your tank if the device you use to remove the air fails.
Other than that, mine worked great and was quiet but a PITA.
I replaced with a Lifereef. www.lifereef.com Really amazing build quality. Good heavy acrylic and excellent craftmanship. Pricey compared to some others but well worth it, still affordable. Not always available as it's a small company and he builds his different products at different times. Mine took close to a month from the time I contacted them until I got it, but only about 10 days after collecting payment.
They are also failsafe. If the power goes out or pump fails, it will NOT lose siphon. Probably the best built overflow out there. Be careful of those that claim to never lose siphon. Some of the cheapies are not failsafe eventhough the concept to make them that way is pretty simple.
I just recently purchaseda lifereef overflow slim. got it with a mag7. easy to setup tested the wont loose suction,Had 3 powr outages today sump did not overflow and and di dnot loose syphon when power came back on. Very well made. yes its a little pricey but worth it