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View Full Version : where are the bubbles coming from?


benf
01/30/2007, 07:34 AM
Little info 1st on setup....200gal Acrylic tank with 5ft overflow with 3 2" durso's draining into a 3" pipe into a 35gal sump (soon to be replaced with 47gal sump), my return pump is a Sequence Hammerhead with 2" inlet and outlet with a three way into 2 1.5" returns and the third line splits again into my chiller and refuge. I have ball valves on everything to control my flow. Tank has been up for just over a week now and last night i started getting bubble blast every couple of mins in the tank. At first i thought it was low water in the sump, but even though i have more in there i still get the bubble blast in the tank. I should mention that on the inlet side of the pump inside the sump i have placed a small 2" pipe with a 45 degree angle facing toward the bottom of the sump, thinking it would be less likely for the pump to suck air if the water lever drops from evaporation.

So, any ideas what to ck? where the air is being sucked in from. Only other thing i could think of, is my outlet for the refuge is at the water level and the flow needs to be increased so mater water and less air returns to the sump, but even that being the case it returns into a filter sock for that very reason...cut down on bubbles. I am at a lost!! :(

BlueCorn
01/30/2007, 06:26 PM
Be careful not to restrict the pump inlet as it can cause cavitation. It's also possible that you've got trapped air in the plumbing somewhere that will take a while to get flushed out. Only being one week old that's quite possible.

AZDesertRat
01/30/2007, 06:36 PM
Sounds like cavitation to me. Normally the inlet is larger than the outlet and in your case with a 2" inlet and multiple outlets you have a greater surface area on the outlet then the inlet. Have you tried squeezing the outlet valves down slightly or shutting one or two outlets off all together (increasing head) to see if the bubbles quit? Also have you tried removing the elbow on the inlet that is making the water change diirections (which is a restriction).

benf
01/30/2007, 07:35 PM
i believe i found the problem...the union between the sump and the pump inlet was slightly loose...i gave it a turn and so far no bubbles...(fingers crossed)

Thanks for the suggestions though!!I will take some of your steps if it happens again though!

Thanks again,
Ben

angelopasto
01/30/2007, 08:04 PM
I have been following this thread and I think I just learned what MY problem is. I have a GenX 100 pump with a 1" intake from my sump to a 1" outlet split to two 1" returns. My pump sits 6" below my sump so I placed a 90 degree angle on the intake side of the pump and I have a ton of bubbles. The only way to cut down on the bubbles is to cut back the flow on the output. If I cut the input side I still have bubbles. Can it be cavitation??

AZDesertRat
01/30/2007, 09:36 PM
Yep. If you have a 1" outlet especially if it splits into two outlets you need at least a 1.5" suction line. You always want the total surface area of the return to be slightly less than the suction or have some head or resistance to flow (valves, fittings, reductions, SCWDS, etc.) against it to balance the pump out.