Quieting in sump pumps - test results

[don_chuwish]

So in my initial testing with just the Waveline DC-6000 return pump I was pretty happy with the noise level coming from the sump.

https://www.reef2reef.com/threads/finally-going-big-120g.211632/

Then I fired up the Vertex Omega 150 skimmer. That's a lot louder!

So today I grabbed a few things, first from Dollar Tree - $3.00:

And from Staples, a basic neoprene mouse pad, about 1/8" thick - $4.79:

I put things through various iterations. Taking two samples for each, about 5 inches from the sump using AudioTools RTA app on my phone. Something to note about dBA, from what I understand, a 3 dBA reduction equals a 50% reduction in perceived noise level. So every 3 dBA you're cutting the noise in half.

Baseline:
Return pump only 51.9 - 52.1 dBA
Return + skimmer 55.5 - 56.1 dBA

Tests:
Return pump only, on mousepad 49.2 - 49.6 dBA

- perceptible reduction in one particular high tone​

Return pump only, on sponge 49.3 - 49.4 dBA

- similar numbers, but somehow sounds worse than mousepad​

Return on sponge + skimmer pump on mousepad 52.1 - 52.7 dBA

- sounded MUCH better than baseline​

Return on sponge + skimmer body on mousepad 53.1 - 53.4 dBA
Above, plus Skimmer pump on sponge 52.6 - 53.1 dBA

Skimmer pump and body on knee pad, return on mousepad 49.9 - 50.5 dBA

- best subjective result as well​

Above, plus putting the doors on the cabinet 38.0 - 38.2 dBA (sssshhhhh!)

According to the RTA charts, most of the SPL comes from lower frequencies, which are hardest to block. So adding foam, etc., to the inside of the stand probably won't help.

Worst result:

Best result:

The knee pad seems like a great material but it really wants to float, so if I use it I'll silicone it down. But it's also about 5/8" thick, lifting the skimmer more than I want. It also makes it a bit wobbly.

I think I'll get more mousepads and maybe double them up for a 1/4" lift. Best to silicone them down too so they don't come loose and block a pump intake.

 

[AZDesertRat]

Best thing I have found for quieting return pumps is a section of vinyl tubing between the pump discharge and any ridgid piping. The relieves the pump of any stresses due to minor pipe misalignments and breaks up vibration which travels through the ridgid piping.
Wouldn't work for a close coupled or self contained skimmer though. I'm all for anything that reduced the noise.

 

[don_chuwish]

Yep, already have silicone tubing between pump and skimmer and pump and return manifold.

 

[don_chuwish]

Another thing I noticed - you can feel the difference. With nothing under the pumps if I put my finger on the sump rim I could feel the vibration - but with the mousepad, etc., in place it was dead to the touch.

 

[don_chuwish]

I think I'm going to try some silicone pot holders - see if they do any better. Found these - even like the red!

https://www.amazon.com/gp/aw/d/B015TL2LBK/ref=ya_aw_od_pi?ie=UTF8&psc=1

 

[jamie callard Verified Sponsor]

I just accept the noise at this point

 

[don_chuwish]

So today I tried some silicone pot holders. Just over 1/4" thick and a great color.
http://www.amazon.com/gp/product/B015TL2LBK

One is the perfect size for under the skimmer body, cutting the other made it work for the two pumps.

Noise level results:

Return pump alone, on pot holder: 47.8 - 48.4dBA
Return + Skimmer on pot holders: 50.5dBA

With the doors on: 38.7 - 39.2dBA

So really no improvement over the previous tests, but a much better solution I think.

 

[acer]

Following along . Great thread. Super ideas for my summer project.

 

[TylerS]

I was reading your main build thread and thought I'd give you some ideas. It looks like you've done some isolation since you don't feel vibrations anymore, but you didn't get the main source of the sound that you hear.

I'm not sure if you can do to much about stopping the generation of the noise from the pumps (other than buying quieter pumps), but what about isolating the noise to under the stand? You could try lining the inside of the stand with mass loaded vinyl. One example here http://www.amazon.com/Loaded-Vinyl-Square-Acoustic-Barrier/dp/B007N3356S. Maybe even put it between the sump and the base. You could also try some sound absorbing foam. http://www.acousticalsurfaces.com/b...he-difference-between-blocking-and-absorbing/

A problem you'll run into is your vent holes for the fan. I would guess this is the source of a lot of sound exiting from under the stand as it is now. Have you tried blocking them off to see if that effects the sound? Sound can travel through the smallest holes. You could try to completely seal up the stand? For example: use weather stripping around the doors and caulk all cracks.

Full disclosure, I've never tried this personally, or read of anyone doing it. I would guess some of those products off-gas VOC which I've read can effect things in the tank (run carbon for a while if you try this). To control sound I plan to run a basement sump and put sound isolation into the walls and ceiling of the sump room.

 

[don_chuwish]

Thanks, I'm quite familiar with MLV actually - I did a huge sound deadening project in my car where I used a lot of it.
In this case I think I have it quiet enough at this point. With the doors on we barely notice tank noise other than the occasional water sounds.
Definitely the penetrations for ventilation are going to let some noise through but they are necessary. The louvered soffit vent cover actually does a good job of blocking some noise and the fan hole is a couple of inches from a wall, so not much caries from there into the room.
Any additional effort at this point wouldn't bring much benefit.

 

[TylerS]

Oh. Since your ending sound db and starting were the same I thought you were still looking for improvement!

 

[mfinn]

I think I'm going to try some silicone pot holders - see if they do any better. Found these - even like the red!

https://www.amazon.com/gp/aw/d/B015TL2LBK/ref=ya_aw_od_pi?ie=UTF8&psc=1

I've been using a silicone hot pads for several years under skimmers and internal pumps.
Always seemed to help a little.
But I haven't seen those thicker hot pads before.
May have to order a couple to have on hand.

 

[don_chuwish]

Oh. Since your ending sound db and starting were the same I thought you were still looking for improvement!

Oh I see the confusion - the hot pads weren't much improvement over the mouse pad and knee pad is all. Just a better material to use overall.

 

[don_chuwish]

I've been using a silicone hot pads for several years under skimmers and internal pumps.
Always seemed to help a little.
But I haven't seen those thicker hot pads before.
May have to order a couple to have on hand.

Yes there was a thinner version of the same one. The only irritation I had with them is that the honeycomb pattern wants to hold little air bubbles in each cell - so the whole thing tries to float. But a good shaking underwater releases all the bubbles and then it sinks fine.