Quick question about HOB overflow and aqualifter

[g8rorchid]

I have a simple HOB overflow with a U tube and I am thinking about adding a pump to keep the siphon at a steady rate. Everything that I have seen requires drilling the U tube and attaching the air lines from the aqualifter that way. Can the air line just be fed up the tube? Would a different pump be better? Could a pump with a single air line work? Or no, because it is almost certain that water will be sucked up along with the air and so an outlet is required?

Thanks in advance!

 

[mcgyvr]

The aqualifter is a great pump for that application..

You could also use a powerhead with a "venturi" nozzle on it..
Like this..http://www.drsfostersmith.com/images/Categoryimages/larger/lg-77712-61037-fish-supplies.jpg

And yes.. It will always be sucking water through it (and air when/if it gets in there)..
So one end of aqualifter sucking water out and the other end allows it to drain into the tank..

And you could push the suction line up the U but it may just act as a restriction for stuff to get stuck on it (loose algae,etc..)
In the past when I had enough guts to run a HOB I just drilled a hole and stuck a small barb to male thread fitting in the hole and epoxied/glued it into place then just attached the suction line to the barb side.

 

[jml1149]

I have a lot of experience with this, as I ran a 29g tank with a hob overflow for an couple of years.

Never again.

Now, if it's the only option, I would recommend NOT doing this. I also thought it was a good idea and for a while, I did what you were suggesting, I fed the tube up the pipe and let the aqualifter keep the air out. Problem is, on more than one occasion, the aqualifter failed, and allowed the tube to break siphon. Big big mess.

So I said screw it and ran with no pump, never had a problem.

 

[jml1149]

Well, how simple of an overflow are we talking?

 

[Vinny Kreyling]

A "U" tube in the correct overflow box should not need any attention --
IF the flow rate is sufficient enough to pull any air bubbles completely through the tube & out the other end.

 

[mcgyvr]

A "U" tube in the correct overflow box should not need any attention --
IF the flow rate is sufficient enough to pull any air bubbles completely through the tube & out the other end.

That is correct... Of course that also means we must know the "sufficient" flow rate and be continually monitoring it..

 

[ericarenee]

One thing to note..

Be sure to use a check valve just above the hole in the top of the u-tube This will insure that if the aqualifter pump stops working or a hose ruptures it will not let enough air to feed back into the U-TUBE to stop siphon....

Its just a bit of extra safety..



i hate check valves but i think this is a place you need to use one.. if it fails your in no worse shape then you would be if it was not there.. If you get a back flow issue and its not there your in for a flood..

 

[GimpyFin]

A "U" tube in the correct overflow box should not need any attention --
IF the flow rate is sufficient enough to pull any air bubbles completely through the tube & out the other end.

^^This^^

I've had a hang on overflow (Eshopps) on my small tank for about 2 years now and it's worked flawlessly. No bubbles, no aqualifter, etc. If you get bubbles accumulate in the top of the tube, the return flow needs to be increased (Or use a smaller diameter u-tube.)

 

[g8rorchid]

Thank you for all of the replies. So I gather that aqualifters are contested. The way my tank is set up, I don't totally lose siphon, it just slows. Sometimes for no reason and sometimes when the water level has lowered enough in the sump. (An ATO isn't an option). I wouldn't care about having to manually restrengthen the flow, but I am in the process of adding a canopy and it will block my ability to do this. Any other thoughts?

 

[Vinny Kreyling]

You have to play with the height of the inside overflow box to get more flow quicker to pull any air through.

 

[g8rorchid]

The overflow box is as low as possible in the tank.

 

[Vinny Kreyling]

Can you elongate the slot?
It might have to be raised too, you have to see.
Every tank has it's own parameters.