Overflow Breaking Siphon

rexman · 12-23-2004, 04:46 AM

help!!!

My newly installed overflow is breaking siphon. Apparently I have some bubbles in the water that are accumulating in the top of my overflow box. After several hours they cause it to break siphon.

I have hooked the air removal fitting on the overflow to the venturi intake on my skilter (it does nothing to remove the air).

I have hooked the air removal fitting on the overflow to the venturi intake on my rio 138 GPh powerhead and it does nothing to remove the air.

I put fiber floss in the overflow intake. this has slowed down the accumulation, but i am still getting air bubbles in the overflow.

How can I make sure that I keep the air from accumulating in the overflow box?

I am afraid to leave home for more than 8 hrs.

Any advice would be appreciated..

Craig Manoukian · 12-23-2004, 05:13 AM

Can you lower the level of the intake box and increase the water flow thus reducing the air accumulation?

szidls · 12-23-2004, 05:20 AM

I had the same problem in an overflow box that has a U-tube. I increased the return pump flow so that the O-F box is running at capacity. The air bubbles were sucked completely through the u-tube and not allowed to collect at the top. Hope that helps.

Scott

skennelly · 12-23-2004, 06:11 AM

Since you stated there is an air removal fitting on the overflow I am assuming your using a CPR. I have the same overflow. A regular powerhead at 135 gph isn't going to cut it. If you are going to use a regular powerhead for this it ought to be 400+ gph in strength. CPR recommends using a rio 600 rejuvinating powerhead ( what I use ) or an Aqualifter vacuum pump to remove the air.

The CPR is a good design with flaws. No matter what air bubbles seem to collect regardless of the amount of flow. I kind of believe the theory that CPR put on the air nipple to solve the problem of air accumulating in the c tube.

Don't get me wrong I love how quiet the CPR is, but it does have design flaws. My regular overflow hardly ever collected air in the C tube and if it did a shake of the tube would move all the air pockets out.

whooo. long post.

Sean

Birdlady · 12-23-2004, 04:54 PM

I have the same cpr overflow as well. I got the aqualifter pump and have no problems now

It is only like, fifteen bucks.

rexman · 12-24-2004, 02:24 AM

Thanks for the great advice!!!! I will try the aqualifter pump. I am using polyester floss to control the air bubbles now and it seems to be slowing them down.

geologeek · 12-24-2004, 04:06 AM

I dont understand how attaching the line to a powerhead works! well i do but what happens when the power goes out? does the syphon not get broken?

Do you use a one way valve to stop air getting back to the over flow?

Would putting a nylon tight over the box help with stopping the air getting into the unit?

Birdlady · 12-24-2004, 04:39 AM

http://www.marinedepot.com/md_viewIt...product=CR1515

Here is a pic of the box I have, as you can barely make out, the top front corner of the black section has a small airline nipple...you attach airline tubing to it and attach the other end to a Venturi style powerhead (to the air inlet opening)

As the powerhead draws through the inlet, it sucks the air out of the overflow box, if there is any. When power goes out, and starts back up again, the powerhead draws out all the air and restores the siphon. The box itself prevents all of the water from exiting the box, enough that siphon can be restored after power failure.

Or, I use the aqualifter pump which sole purpose is to draw air up and spit it out a different line.

Sorry so long!!!

geologeek · 12-24-2004, 04:44 AM

I get it thanks! But what if the powerhead fails ( i know a slim chance), gonna be awfull messy!, would it not be better st suck out the air and put on a clamp? That way the syphon will always be in place!

Birdlady · 12-24-2004, 04:48 AM

The nature of the cascade over the side of the box creates bubbles...they build up and break siphon. And unlike the 'C' tubes, you cannot get the flow fast enough to push the bubbles through. Mine runs full out at 800 gph.

I personally, have my setup so if my overflow fails, the pumps in the sump will run dry. Conversely, if the pumps in the sump fail, the overflow will not spill over the sides of the sump. I would say is is failsafe...but I don't want to jinx it!

I figure a burned up pump is a small price to pay, relative to a new living room floor or a whole tank of critters