Overflow box loosing prime.

[mckaax]

For some reason when the water falls into the box it is creating bubbles, the bubbles then get sucked into the pipes. This is causing me to loose my prime in one of my tubes. I have tried moving the box around and I have the tubes as far away from the bubbles as possible. I was wondering if it was possible to fabricate some sort of shielding inside the box. Or do any of you guys have a better idea?

 

[mike murphy]

I did not have that problem on my single overflow but when I went to a double I found the situation with the bubbles but my pump seems to flow fast enough to suck them through before they accumulate at a high point but they are small. I try to keep them moved toward the center away from the outer walls as far as the siphon tubes go.

 

[augustwest]

Are these siphon or powerhead driven?
I run 2 CPR overflow boxes which are siphon driven. They have a fitting in the top to suck out the air (and to start the siphon - mmm saltwater in the mouth). I have each attached to a Tom's lifter pump ($11). I would check out the CPR's and see if you can mod your boxes to do the same.

 

[saltymac]

Try to reposition the depth of the box, not as deep maybe, or tilting it to the side away from the tube. ? never had that problem.....good luck

 

[natclanwy]

Bubbles are normal with overflow boxes the problem lies with the flowrate through the overflow if it is too low the bubbles will accumulate at the top of the U-tubes. Your return pump should be rated at least 2/3 of the maximum flow rate for the overflow box after headloss. What pump are you using for the return and what size is your return and overflow plumbing?

 

[mckaax]

Originally Posted by natclanwy
http:///forum/post/2574680
Bubbles are normal with overflow boxes the problem lies with the flowrate through the overflow if it is too low the bubbles will accumulate at the top of the U-tubes. Your return pump should be rated at least 2/3 of the maximum flow rate for the overflow box after headloss. What pump are you using for the return and what size is your return and overflow plumbing?
Well i think my pump is a little small but I was thinking about refabing the box some so the bubbles cant reach the tubes. But yes I think I need a larger pump.

 

[natclanwy]

You are taking a risk by running a pump that is too small you can try and prevent the bubbles from entering the tubes but there is a good chance that you will eventually have a flood any way. If you don't want to replace the pump try removing one of the U-tubes, that will increase the flow rate on the remaining u-tube which will help prevent the bubbles from accumulating. Be sure and watch it for a while to make sure that one u-tube can keep up with the pump.

 

[renogaw]

if you have a sponge filter over the retun pump's inlet clean it out. I remember having this issue because of that as well. but yea, if you can get a bigger pump.

 

[bkvreef]

Originally Posted by mckaax
http:///forum/post/2573877
For some reason when the water falls into the box it is creating bubbles, the bubbles then get sucked into the pipes. This is causing me to loose my prime in one of my tubes. I have tried moving the box around and I have the tubes as far away from the bubbles as possible. I was wondering if it was possible to fabricate some sort of shielding inside the box. Or do any of you guys have a better idea?
I have a similar problem with mine. I am almost 100% sure that it's because my pump isn't big enough. The water from my sump doesn't return fast enough to keep the overflow u-tube full. I was concerned that my pump would be too strong so I deal with redoing the syphoon (whatever you call it) every 2 or so weeks. Not a big deal for me but it is somewhat annoying.
Could you get a larger pump and put some type of pvc joint to control the flow and lesson the flow from a stronger pump?

 

[scsinet]

Originally Posted by bkvreef
http:///forum/post/2575249
I have a similar problem with mine. I am almost 100% sure that it's because my pump isn't big enough. The water from my sump doesn't return fast enough to keep the overflow u-tube full. I was concerned that my pump would be too strong so I deal with redoing the syphoon (whatever you call it) every 2 or so weeks. Not a big deal for me but it is somewhat annoying.
Could you get a larger pump and put some type of pvc joint to control the flow and lesson the flow from a stronger pump?
I agree...this smells like insufficient flow rate.
You can't stop the bubbles from entering the U-Tube, but the flow rate through the tube needs to be fast enough to "wash them through" so they don't accumulate into a growing bubble at the top. You may need to try a smaller diameter U-Tube... if you can find one.

 

[natclanwy]

Originally Posted by bkvreef
http:///forum/post/2575249
I have a similar problem with mine. I am almost 100% sure that it's because my pump isn't big enough. The water from my sump doesn't return fast enough to keep the overflow u-tube full. I was concerned that my pump would be too strong so I deal with redoing the syphoon (whatever you call it) every 2 or so weeks. Not a big deal for me but it is somewhat annoying.
Could you get a larger pump and put some type of pvc joint to control the flow and lesson the flow from a stronger pump?
Yes you can get a larger pump and use a valve to restrict the flow or set up a "T" to divert some of the flow back to the sump the latter is probably the best solution. Just keep in mind if heat is an issue in your tank a larger pump means more heat and if you add a valve and restrict the flow it causes the pump to work harder and generate even more heat so try to size the pump so you don't need to divert or restrict the flow or at least keep it to a minimum don't buy a 1600gph pump and restrict it to 1200gph.

 

[mckaax]

Originally Posted by SCSInet
http:///forum/post/2575422
I agree...this smells like insufficient flow rate.
You may need to try a smaller diameter U-Tube... if you can find one.
BINGO!!
This is a perfect Idea and will save me the hassle of re pluming the return line

 

[sh00tist]

If you arent sending enough water to your tank to run 2 u-tubes then you need to remove one and only use one. Ive never seen a smaller diameter u-tube though they may exist,I do think one could be DIYd however