Opinions on CPR Hang On Overflows

[jeffandkelly]

I want to convert my 46 gallon bowfront that is currently freshwater to a reef and get ride of my innovative marine dropoff. I know that the aquarium is tempered glass so I am not going to try to drill it.

What is the opinion on these? We want to run it into a sump and not have HOB everything.

 

[bhodges82]

If you can't drill it then hob is the only way to go. I used an Aqua c hob skimmer before and it worked decent, I'm sure there are better options out now but I don't have personal experience with any.

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[jeffandkelly]

If you can't drill it then hob is the only way to go. I used an Aqua c hob skimmer before and it worked decent, I'm sure there are better options out now but I don't have personal experience with any.

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So you would not use the external overflow?

 

[bzb]

15 years ago, all I used were hang on overflows. They work just fine, but are not without issues - primarily losing siphon due to bubble buildup. The most difficult task for me was matching the overflow rate to the return pump rate - that typically would ensure no bubble buildup. I don't ever recall losing siphon from power outages or stopping the pumps, typically the system would just restart with power to the return.

That being said, a few tips from my (albeit dated) experience:

- Use a clear siphon (U) tube, that way you can check every couple days for any bubble buildup
- A lift pump is handy in the box, but then you need a bigger, uglier box in the tank
- Test for power outage, make sure sump can handle
- Test for siphon break, make sure tank can handle (or a float switch could stop the return pump)

 

[ichthyoid]

Fwiw-
The CPR brand of hang on overflows have a fitting which can be connected to an Aqualifter pump to not only prime, but periodically re-prime the overflow.

I say periodically, because last I checked the Aqualifter is not rated for continuous duty.

Most of us that have used hang on overflows in the past would not willingly do so again. The risks are too great & convenience of a drilled overflow cannot be overstated.
My $0.02

Here for more info-

http://www.cpraquaticinc.com/cs-overflows

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[Cook]

If you decide you want to try it, I have an older CPR overflow you can have. The key is to make sure if siphon is lost, the sump can’t overflow the tank.

 

[jeffandkelly]

Thanks everyone. I think I decided to go the HOB route. This seems like it may be a disaster