Well the last time I stated my opinion (and the thing here is that it is just that, AN OPINION) on what I view as a poor design and generally crappy overflow... yes, the CPR one, I got bashed purty good. Bashed by all the CPR users of course... I guess no one wants to hear their stuff is junk.
The CPR overflow is the ONLY overflow I have ever used that failed on me...not once but twice! And believe me.... overflowing a tank when you live in an upstairs apartment is not regarded too highly by the tenant below and of course Mr. Landlord.
Any overflow that requires the use of an additional pump or powerhead to insure it working properly to me couldn't be more of a red flag. There is so much surface area the way the overflow is designed that if there is not sufficient flow going through it it starts building up bubbles in it... thus the powerhead to keep it primed. True this can happen with a tube style as well but much less likely.
Soooo, what I'm saying is I would go with about ANY other overflow than the CPR. Hey it's just an opinion folks, okay? Besides you don't have to take my word for it... there is plenty of feedback available to those who would like to seek it out.... overwhelmingly negative I might add.
To you users of CPR's... hey no probs? Way cool! I just happen to have this Pavlonian response to the intials... instead of salivating I get my panties in a bunch!....lol