Stopping Air insertion from Power Head Venturi
Problem:In my marine aquarium I'm using Hagen Power Head 402 with a Aqua Clear Quick Filter. But the quick filter is just an additional help in removing some wastes. The main reason why I bought the Power Head 402 was to use it as a wave maker. But I don't want the power head to let out the air bubbles into the water. But that happens even if the air hose is fully closed. Why is that? How can I make a water move without these very small water bubbles?
You must ensure the Power Head cannot get air in to the Venturi and that the impeller is never above the water line.
1) Place the unit fully under the water so no air contacts the unit.
2) Take the air line that came with it, tie it in a knot to close it completely. Then isert the closed tube into the Power Head's Venturi hole. There is an additional hole as well, so the warning to keep the unit fully submersed is very important to eliminate air insertion.
Alternately take a small piece of the airline and squirt a bit of silicon to block it, but leave about a 1/4" of the end without any filling to make it easier to place the airline into the Venturi. If it is completely plugged, the line may not compress enough to allow easy entry into the Venturi hole.
Finally, you might find that submersing it entirely will eliminate all air bubbles anyway, without knots or plugs, the really important point is that the output must be below the surface enough that it cannot draw air into the system to blow it out. Simple submersion often cures this.
Thanks for your answer on the air bubbles problem. The problem is that even with the whole unit placed fully under the water and fully closed air line, the air bubbles still are blowing into the water. Those are very small bubbles. Much smaller then they normally occur when the air line stays open. I was thinking if is possible that impeller by its fast rotation makes the bubbles itself?
It is always a possibility, but to continually create air bubbles, the air must be coming from somewhere. That is why I suggest that you ensure the entire unit is placed under the water, if the air is entering the system from the input, it should slowly eliminate the problem as the bubbles break at the surface and have no way to be replaced. You might want to shut off the system for a few minutes to allow any air in the water to rise unhindered and break at the surface. Another possible place where air is entering is where the water is boiling at the surface. Although this is pretty desirable, it may mean you must move the powerhead away from the filter agitation source to allow the bubbles entering to break at the surface rather than get trapped by the PH input.
As far as the Powerhead actually manufacturing air under water, that is really not one of the traits I have ever encountered in a powerhead. Air production in a properly installed PH is not a factor. The system does not cavitate to chop up and create bubbles in normal operation. That is why I feel you must find the original source of the air being input into the Power Head. I have always seen that when no air enters the input, and no air is allowed through the Venturi and starter holes, then no air can be output. Hope that helps a bit, look for a source of air, Power Heads really are not able to spontaneously generate bubbles to the best of my knowledge.
. The 50, which I'm currently using, is the worst of the two, blowing poofs of bubbles every 15 seconds or so. It is totally submerged and nowhere near any source of bubbles. It doesn't really make the tank look bad but I feel, due to the cavitation, it's pulling dissolved oxygen out of the water and sending it to the surface as large bubbles. My fish seem fine but I still don't like the idea. I have $70 invested in these pieces of junk!:mad2
