HOB overflow systems: What's your opinion?

[dleomd]

Hi all, I'm considering setting up a standard 150g with HOB overflows. I'm hearing that they are not worth the hassle and are prone to flooding problems. Would greatly appreciate your input! Thanks

 

[rallysman]

I've had issues with CPR style, I've never had issues with the style that has the tube(s) connecting the inside and outside chamber.
Even with an aqualifter I've had the CPR style get air in them, but I've never touched the type I have with the tubes and it has been running over 2 years.

 

[dleomd]

Thanks rallysman, when you say "issues" what do you mean? Did you have flooding problems? that's what worries me most.

 

[rallysman]

I would have if I didn't catch it in time. Air got in the CPR style and the level of the tank was creeping up since it couldn't quite keep up.

 

[dleomd]

Were you using an aqualifter?

 

[rallysman]

On 2 occasions I was. The diaphragm on the aqualifter got gummed up even though I had the prefilter on it. If you use an aqualifter I suggest changing the filter and cleaning or replacing the diaphragms every couple of months.

 

[dleomd]

appreciate the advice!

 

[dennisdeng2002]

Drilling would be the most reliable way, especially since your tank is setup yet. Otherwise I would get a U tube overflow, like a lifereef overflow, the most reliable hob overflow on the market.

 

[JL]

I don't understand how flooding could happen w/ HOB overflows. The HOB siphon will cut off once the water level in the tank gets below the box grooves and the return pump will only fill the tank till the sump is dry so how does flooding happen? The only way I could see it is if you lose power and a back siphon starts w/ your return and that depends on how low the return output is in comparison to your water level in the tank. This is easily remedied w/ a check valve. If any it'll be a small amount. I've never had an overflow problem w/ my HOB's.

 

[rallysman]

I don't understand how flooding could happen w/ HOB overflows. The HOB siphon will cut off once the water level in the tank gets below the box grooves and the return pump will only fill the tank till the sump is dry so how does flooding happen? The only way I could see it is if you lose power and a back siphon starts w/ your return and that depends on how low the return output is in comparison to your water level in the tank. This is easily remedied w/ a check valve. If any it'll be a small amount. I've never had an overflow problem w/ my HOB's.

The biggest issue is if air gets in the overflow, which happens a lot with the CPR type. The sump doesn't flood, the tank does.