Mag+SCWD=Noise

[JeepersReefers]

Just finished a closed loop system for my 46g zoo tank Amd mych to my dismay its noisy. We had the same problem with cavitation (sp?) on a friends closed loop system. Every thing that was suguested to him i incroporated in to my system. And it's still doing it

The Closed Loop"
is a mag 9.5 with a 1" intake and a 3/4" out in to 2X SCWDs. The pump sits on the floor (per RS members suguestion). The return lines are 3/4" flex tubes.

What Gives???

Thanks Dane

[BoomerD]

o.k., couple of questions...where is the sqwd mounted? Low or high? (Pertains to the amount of head pressure for th e pump) Is it hard plumbed to the pump or vinyl tubing there too? Where is the noise coming from? Pump growling? vibration in the lines? SQWD itself?

[JeepersReefers]

Sorry for the vague and hastily typed post.
The SCWDS are mounted half way up the thank from the floor. (sincityreefer had the exact same problem with a mag 18 closed loop, but his was mounted on the stand not set on the floor.)
The return side is made entirely of vinyl tubing.
The noise is comming from the impeller section of the pump. It sounds like there is air in the lines if i'd have to discribe the noise.
It is definatly the pump not the SCWDS or any thing elese for that matter.

[BoomerD]

If you remove the scwd, does the noise go away??

[sincityreefer]

cavitation is the issue... fix that and your set to go. My setup would have workd great if i could have managed space for some 1 1/2 intake pipe. bigger intake pipe, with less bends.. and i heard somewhere that upsizing the outflow side right when it comes out of the pump then resizeing it back to the normal 3/4" after a few inches. like use a 3/4 to 1 1/4" bushing then a small <4" 1 1/4" pipe section then resized back to normal 3/4.... Not sure if thats true or not, just some suguestion i heard..... HTH

[BoomerD]

I ran a closed loop with a Mag 12 for over a year, fed by a piece of 1" vinyl tubing, and with 1" PVC output that was split into 3 outlets from a manifold. Not a sound...

[JeepersReefers]

Hmm.... The only common factor btewene the two noisy closed loop systems is the SCWDS. I will try the system W/O the SCWDS this afternoon

[sincityreefer]

boomer, i think the vinyl tubing to feed the pump is a good idea. from what i understand the more bends and kinks you have on the inlet side the more likely you are to have cavitation. It almost is like reverse head pressure kinda.. So vinly tubing would not have the 90 degree bends that PVC does. However the head pressure on the outflow side should not be an issue at all.
Jeepers, did you put a ball valve on the outflow side of the pump? if you did try slowly closing it and if the sound stops after youve tweaked the ball valve a bit, then it is 100% without a doubt cavitation and, as you would now beable to see the head pressure is not the issue, as weve just increased the head pressure dramatically by closing a ball valve 1/4 (or more) of the way. (this is exactally what my closed loop did, FYI) So the removal of the squids and the reduction in head pressure will likely make your pump LOUDER, until you fix your cavitation issue. The other possiblility is that you have an air leak in your PVC somewhere. did you glue all the pieces together? even the ones over the tank that are out of watter? Teflon tape around the pump fittings? I have heard of all of these things causing air leaks and producing a smiliar sound and effect as cavitation... But it sounds like you are dealing with cavitation if i had to guess. i would try vinly tubing on the intake like boomer mentioned, maybe a little larger than 1" if you can squeeze it in there.

[BoomerD]

When I built mine, I got a 1"x18" "J"-Tube for over the back, 1" vinyl tubing to a 90, with a ball valve and union, then the poump, ball valve & union again, and up to the 1" manifold and 3/4" risers to the tank. There IS a 90, but it's several inches away from the pump inlet. There's a formula for how far away from the inlet a 90 should be, not sure what it is, X# of times the diameter of the piping going in, but don't remember what "X" is...

Here's a link to PUMP SCHOOL , but it doesn't cover that aspect. I'll find it and get back to you on that...

[JeepersReefers]

Removed the SCWD and its exactly the same thing. How far from the pump does the 90' have to be... Mine is only an inch or two. Could that be the problem?

[BoomerD]

It could definitely be the problem...I think the distance I tried to find was 8x the diameter of the pipe, which would be 8" from the nearest 90 to the pump. Apparently, the 90 causes a lot of turbulence in the flow, which translates into cavitation inside the pump. BEFORE you comppletely re-do everything though, I'd try taking the pump out of the loop, cleaning it out to make sure there's NOTHING inside the volute, (even if it's brand new) then testing it with a garden hose connected to it for a water supply or something similar to be sure it's not just a noisy pump. It would be the pits to go through all kinds of tests and re-configurations then find out later that it was the pump all along...

[sincityreefer]

Originally posted by JeepersReefers
Removed the SCWD and its exactly the same thing. How far from the pump does the 90' have to be... Mine is only an inch or two. Could that be the problem?

well not to say i told you so.... but, i told you so... I think boomer is on the right track with his formula. 90's do cause an awfull lot of turbulance vinly tubing is probally the easiest way to go... I also like his idea of using a J tube to draw the water out, a gental curve causes much less turbulance than a 90.

[Witfull]

just to add,,,i try not to use 90's. i prefer 2-45's to soften the angle.