Which overflow is better? Top or bottom intake?

[suds1421]

Hey everyone,

Looking into overflows for my 75 gallon african cichlid tank.

I would like to run an undergravel jet system to keep the sand clean. My question is which overflow style would be better to keep the messy cichlids cleaned up?

This one?

Or:

(Images copied from other posts, thanks to the original creators )

I don't really have a preference on which one to use... Just want the one that flows the best and will keep the "stuff" moving so that my sand stays clean...

 

[bdog]

The first one won't flow as much as the 2nd. Most of the flow rates you see on here will be for the 2nd one. You can add another larger tube over tube B so that it sucks water from the bottom. I'm think there's a picture of that in the sticky.

I would keep reading, do a search on overflow noise. I jumped right on this and built mine without reading as much as I should've. Now I might end up re-doing mine. The good thing is that PVC is cheap so screwing up isn't that big of a deal assuming you have time on your hands.

 

[suds1421]

I'm not super worried about noise, the back end of my tank will be in a utility room so noise isn't an issue unless it is REALLY loud and carries through the walls

I thought the second one would flow more, just trying to see if that type of overflow would do a good job of keeping the sand clean when paired with an under gravel jet system.

 

[frnchjeep]

If they are larger cichlids, and splash a lot at feeding time, the second one is prone to sucking air and losing it's prime.

 

[suds1421]

If they are larger cichlids, and splash a lot at feeding time, the second one is prone to sucking air and losing it's prime.

Is this an issue if an airline is hooked to the checkvalve and run to a powerhead? I'll have a powerhead in the tank anyway so it seems like good insurance to hook suction up to the siphon.

 

[frnchjeep]

Dunno, never tried that. I would imagine, though, if it were to suck up an air bubble large enough to break the syphon, the venturi on a powerhead wouldn't be strong enough to raise the water in the overflow high enough. I could be wrong, but I think the powerhead is to suck out the little bubbles that form from normal operation, and not actually for priming it.

 

[prcdslnc13]

Im using the second design. Ive made like 10 of them. 8 were awesome. 2 were audible through the house, I dont know what went wrong with them. I just make sure that you have a way to keep it level. either sitting on the bottom of the tank or otherwise.

 

[Sniperofgods]

i'd go with the second setup its what i am running right now and just make sure to have the pipe labeled c as high as you can go out of site i did mine about 5 inches higher then the e bend and i don't have problems with noise as far as that goes. just my 2 cents tho