[Maverick00]

I have the CPR overflow and for the most part, no issues. However it requires an air pump to be constantly plugged in and "suck" any air bubbles or pockets out of the top of the overflow to maintain the siphon. If this failed, the air bubbles could accumulate and eventually stop the siphon resulting in an overflow. Ive had mine for almost a year with no issues as long as the proper maintenance is preformed. Saying that i have had a couple close calls, the tiny outlet for the pump can be easily clogged by even a small piece of algae you clean off from your glass on the display tank. A drilled tank is defiantly more reliable but if it isnt possible an overflow like mine does work and can be reliable. Ive heard the U type overflows are better but i have no experience with them. I have a VERTEX IN in sump skimmer and i love it, easy to clean, easy to adjust. Thats my experience anyway