Spray bar placement

Alwaysusa

AC Members
Jan 4, 2011
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Are there advantages/disadvantages to placing the spray bar on a canister filter above or below the water line? I assume surface agitation is a benefit when above the water, but it's louder.

I'm not sure if placement has any effect on flow (though if any it must be minimal, right) or fish behavior?

It's an unstocked tank by the way, cycling. It will be heavily planted.
 
most people place them above. They provide surface aggitation for oxygen exchange, and equaly disperse water through out the tank for good circulation without creating too much velocity.
 
I place mine about 2" below the surface in my planted 90 gal It helps keep the CO2 in and unless I forget to clean the filter every now and then I never have trouble with low O2 levels. It's also a lot quieter that way. I do point the openings on my spray bar upwards at about a 45 degree angle so they form little bumps on the surface of the water. It was a little hard to get used to at first since I'd always used hang on backs or undergravel systems where the oxygen exchange was a lot more visible, but even as heavily stocked as I am I don't have any trouble. Some will depend on the relative flow of your filter though. If your tank is just at the rating for the filter (i.e. not overfiltered) then you may want to have it closer to the surface or above. For overfiltered tanks, I'd say a couple of inches below is just fine.
 
i keep my spray bar about 1.5 inches under the water line and angle the holes upwards slightly. this causes the water streams to just break the surface of the water and provides oxygenation/gas exchange.
 
ABOVE WATER=
1) More surface movement==more evaporation and gas exchange.
2) More noisy (splashes)
3) No good using CO2.

Below water
1) More "in tank" circulation.
2) Very quiet.
3) Will not disperse CO2 into air.
 
Thanks all for the answers.

I'm rigging a DIY CO2 kit to learn how it all works - so it's under the water line for me!
 
It really does not matter whether it is above or below. As long as water moves there is an oxygen exchange. It may also be a little more if the water is splashing at the surface. But as far as a great benefit I do not see it.
 
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