Rio 180 powerhead and undergravel filter question

[thartley]

I just bought a Rio 180 powerhead for an undergravel filter. I have looked through the instructions, but I am unable to find the answer to this question. It comes with several attachments/accessories. The two I am wondering about are the 'Discharge adapter with Venturi jet and flow control' (which includes an 'Air stopper') and the 'Air tubing and silencer'.

I am under the impression that I should be able to get the powerhead to add air bubbles into the tank, as well as providing more flow through the UGF. I thought removing the Air stopper from the Venturi on the Discharge adapter and adding the Air tubing and silencer was supposed to suck air through the Air tubing and silencer and mix it with the water it is pushing around the tank. I find that instead, water dribbles out of the tubing.

I have had to choke back the flow through the powerhead to reduce the turbulence in the tank, but even when it was wide open, it still didn't really make many bubbles.

Am I missing something here?

Thanks.

[madasafish]

Welcome to Aquarium Advice, thartley!

Actually, a powerhead *alone* never (as far as I know) adds air to the water stream. You need an air pump connected to the air tubing, and then that will add air bubbles to the water stream. These can be bought for under $10 at your LFS.

If you think about it, a water pump does not create the negative pressure you'd need to suck air from the air line tubing; the water pump simply moves water from one location to another.

I have this sort of a set-up on one of my pleco tanks. It's really a great way to oxygenate the water; and I think it looks pretty cool to have a spray of air bubbles coming out of the water pump.

One recommendation, though... The undergravel filter is an outdated technology. In the 80s and 90s, UGFs were the way to go, as they create a large area of biological filtration under the gravel. However, this area must be cleaned periodically, and requires breaking down the whole tank to do so! If you can afford to buy a Penguin or Emperor HOB filter, or a Fluval or Eheim canister filter, these are much better filters, and will provide biological filtration on the biowheel (in the case of the Penguin and Emperor) or on the filter popcorn (in the case of the Fluval and Eheim).

[docrak]

I have two different brands of power heads on my under gravel setup. Both brands came with a Venturi air discharge. One brand only sucks air when the power head is submerged a certain level bellow the water. Any thing more than an inch and the Venturi doesn’t work. The other brand works to just about any depth and includes a flow control, which allows you to control the amount of air being pulled in. Currently I have only one of my power heads sucking air and it definitely improves the oxygenation of the water. I used to run one power head with an air pump but I find it tends to speed up the flow and causes to much current and surface agitation.

[thartley]

I took the Rio powerhead back to the LFS to discuss the problem. One salesman said it should create bubbles using the venturi attachment. He tested it and couldn't get it to work. He tried a venturi from another package and it wouldn't work either. Then he asked a fellow employee about the problem and this employee said that Rio includes the same venturi with all their sizes of powerheads. He said a Rio 180 doesn't pump enough volume to get the venturi to draw air and that the venturi doesn't start working until about 225 GMH is being moved through it. I would have to go with a larger pump to get that volume. That volume would be too turbulent in my small tank, so it isn't really an option.

The salesman asked if I really needed the bubbles. I told him I thought they were necessary for aeration. He indicated that bubbles are generally for appearance, and that if I aimed the output of the pump towards the water's surface, the movement of the surface water would introduce more oxygen into the water than the bubbles.

So I guess this newbie problem is solved. Thanks for the input.

[Menagerie]

He indicated that bubbles are generally for appearance, and that if I aimed the output of the pump towards the water's surface, the movement of the surface water would introduce more oxygen into the water than the bubbles.

That is true! What you really want is surface agitation.

[center:6a2953b072] Welcome to AA, thartley! [/center:6a2953b072]

[madasafish]

Thartley,

I apologize. I definitely gave you some wrong advice. After posting that powerheads alone don't suck in the oxygen, I tried shutting off my air pump and disconnecting the air line from it. Low and behold, the powerhead sucked the air in! It's less powerful than it was before, but it certainly does work. My apologies to you and docrak for the misinformation!!

You walk a thin line with the option of pointing the powerhead to the top of the tank. If water starts to get low, the stream of water can begin to spray into the hood and light. Be careful with that...