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New tank setup – cavitation issues

B

bconn

New tank setup – cavitation issues ???

Hi. Wondering if anyone could share some insight into what may be going on here. I have a bank of tanks (2 – 40 gallon) being fed from a restricted flow via manifold. I have REALLY limited the water flow during the initial tuning of the setup. Water supply for each trunk comes from ¾ PVC. Both tanks return to sump via 2’’ PVC. The pipe returning water to the sump is above the water line. The water line in each tank is about 1.5’’ below the tank surface. After this is resolved I will plum in the 215 gallon. I would like to see what I may have done incorrectly before moving forward.

The issue that I am having is the periodic cavitation of the return lines in both tanks. The majority of the time they run quiet bit there are times when there are unpleasant gurgles taking place.

Any thoughts from anyone on what could b causing this or what steps I can take to identify/resolve the problem?

Please let me know if I can provide additional information. Thank you in advance.

Bill
 
Phyl

Phyl

Officer Emeritus
Officer Emeritus
Are you restricting the in-feed or out flow of the pump?
 
B

bconn

hi,

No restriction before the pump. I have restricted flow to both tanks via individual ball valves. Water flow is VERY slow to the tanks and I still get the cavitation. At time there does not appear to be any flow leaving the tank. It's is very weird. When I remove the 1'' return line and let the tank drain through the bulkhead back to the sump there is no problem or any cavitation. I would think that if it was a flow back issue it would appear either way.

I'm stumped for now :)

TY in advance.

Bill
 
M

mladencovic

Strictly speaking, I doubt that you have a cavitation effect :) , and if I am reading you correctly, you simply have air being sucked in the return pipe along the water. Air tends to lift, water wants to go down, they create turbulence in the pipe and the pipe resonates it into loud noise. There are couple of ways you could solve that problem. Some people simply muffle the sound by placing sponges and similar things at the entrance of the return pipes or at the top of the overflows. Or you could use the durso standpipe's method of fully submersed water intake with reduced and somewhat controlled air intake that at the same time muffles the resonance characteristics of a pipe.
 
B

bconn

Interesting point to mention. I recently increased the flow rate to these tanks when fine tuning the available output from the manifold to my 215 & 40 breeders. I wanted to see how far I could go without any overflow on the floor and still have additional capacity for the 65 gallon I will be shortly relocating to the basement.

The "cavitation" or gurgle I was hearing has greatly decreased. Much easier on the ears.
 
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