Closed loop pump/water noise - I am going crazy!

[Paula]

I have two closed loops on my 150 with a Blueline 40 HD-X (1270 gph) on each loop. Everything was nice and quiet for months. Then, I noticed that there was a hum eminating from the loops - so I took the pumps off and cleaned them. Boy they were a mess from calcium buildup. I put them back on and the hum still persisted. Then, I noticed that my scwd wasn't working. So, I bit the bullet and bought an Oceans Motion Super Squirt - and installed it this weekend. It seems to be working properly. So now I have 1" spaflex piping thoughtout - and the hum still persists. The noise doesn't seem to be coming from the pumps themselves.

Someone suggested that it might be "cavitation" and I understand the words of the definition of cavitation, but I don't understand the theory behind it - or HOW TO QUIET IT.

There are ball valves at every point of inlet/outlet so I do have the ability to control the flow rate to/from the tank .. . but I have not been able to come up with a "quieting" combination of open and closed.

Please help before I put a sledgehammer through my tank.

 

[dedfish]

Tell us a bit about the plumbing and the size of the drains.

 

[nunofs]

Paula, the way to solve cavitation is to provide a larger intake to the pump... but if you're not seeing bubbles, I'd say it's probably not cavitation.

Sorry, I don't know how to fix your problem, just thought I'd mention that about cavitation. Btw, I had a Blueline pump before and I found it pretty loud (the cooling fan), I ended up replacing it with a T4... but you're saying that the noise isn't coming from the pump, so that doesn't apply. Only other suggestion would be to take the cooling fan apart and clean that (and the grid) as well...

Nuno

 

[dedfish]

Does the plumbing touch the walls or the stand at any point? Maybe some cushioning in those places would help. I know vibration can cause lots of noise.

 

[Paula]

OK - since you asked, I will try to explain the plumbing and equipment. Tank is an Oceanic 150 (60x24x24)
All of the drains and returns are on one end of the tank (the short end) - the tank is in the middle of the room. There are 2 1" drains with dursos, and 3 3/4" returns powered by 2 mag 9.5s (one is straight return with a gate valve on it, the other is a Y which feeds 2 3/4' returns). I have adjusted the returns (using the gate valve) so that flow is quiet and without any burping.

The loops are as follows:
Loop #1 goes out the end of tank (1" blulkhead) throught spa flex into the garage to the blueline HD 40X and back to the tank via 1" spaflex. The water enters from beneath the tank up through the rockwork.
Loop # 2 goes out the other side of the same end of the tank (1" bulkhead) through spa flex into the garage to the blueline HD 40X and back to the tank via 1" spa flex. This loop goes through an OM Super Squirt (plumbed as a scwd) and back to the tank from underneath and switches from one set of rocks to another set of rocks.

No powerheads in the tank. All places where piping could touch either walls or other hard surfaces have been padded. There is a refugium plumbed as a mag 3 from the sump to the fuge (above the tank) and gravity fed to the tank via a 1" flexpipe.

Skimmer is an ASM G3, PM Calcium reactor, PM Kalkreactor used 24x7 as topoff using a dosing pump to match evaporation.

Did I miss anything?

 

[~Flighty~]

A wierd idea, but could you use a stethescope to figure out exactly where in the plumbing the noise is comming from?

 

[NateHanson]

That's just what I was going to suggest. You can probably get a cheap one at a pharmacy. Another trick, that I use on machinery when trying to find out if a bearing is bad or something, is to use a big, long screwdriver. Put the end of the screwdriver on a suspected noise source, and press your ear against the plastic end. (works great as long as you use the right end of the screwdriver.)