Please help - Return pump problem

[FishVet]

My 120-gallon saltwater tank is set up with only sand and saltwater right now. I'm hoping to add something alive soon!

Anyway, I have a 20-gallon sump, no skimmer, this was all just setup a couple months ago. My return pump is doing something awful. Every 5-10 minutes it makes a terrible screeching noise, and tiny tiny fine bubbles come out of the returns in the main tank. It only does this for 2-3 seconds, then goes back to normal for 5-10 minutes.

I thought there might be some air trapped somewhere, and I turned off the pump and inverted it a few times under the water. No air. Turned it back on, same problem.

Please help! And please don't tell me that my pump is going bad after only a couple months!

[C-21 USAF]

The water level is getting too low in your sump and your pump is sucking in air....add more water to the sump????

However, a terrible screaching noise sounds like a bad pump...sorry.

[Shelly]

I try hard to always come up with a positve.....

At least this way if your pump goes now.....you won't lose handfuls of money on lost stock.....Lucky you......

[C-21 USAF]

What brand pump?

I've had excellent performance from Mag-Drive and Eheim over the years...never lost one.

[Gz28]

have you tried taking it apart and cleaning it really good, maybe a tiny piece of crushed coral,rock,sand....whatever is stuck in there.

[phisher]

The water level is getting too low in your sump and your pump is sucking in air....add more water to the sump????

However, a terrible screaching noise sounds like a bad pump...sorry.

^^

I am guessing this too. That's an awful small sump for a 120 its not going to give you much margin for error.

If the pump is definitely not running dry, try removing it and running it in a bucket of water (no plumbing attached) and see if it still does this.

[Gerwin]

cavitation from drawing in air, keep the sump 1/2 full and see if it helps, if not get back with us. and we will go down the check list.

I respectively disagree with phisher though on the sump size, 20 longs will work fine in my past experience and 30l will work as well, it really comes down to the size of the skimmer and other "stuff" you are trying to cram into it.
Heck if you saw the size of the commercial acrylic sumps rated for 175 gal! Phisher you would have a heart attack can you say 10 gallons

[phisher]

As long as you have a good ATO and well designed system its no issue. 20g just does not give you much room for error if/when the power goes out.

Lets do the math on a standard 120g 48x24x24, at 24" tall and 120g that means every inch of tank height holds 5 gallons.
So lets say you run a 20g sump half full consistently you only have 10g of extra space if the power goes out, so if your display drains down 2" you have a mess. That's not considering the water in your plumbing that will drain back or whats in your skimmer or reactors.

I am a master of water on the floor Gerwin, trust me on these things!

[Gerwin]

As long as you have a good ATO and well designed system its no issue. 20g just does not give you much room for error if/when the power goes out.

Lets do the math on a standard 120g 48x24x24, at 24" tall and 120g that means every inch of tank height holds 5 gallons.
So lets say you run a 20g sump half full consistently you only have 10g of extra space if the power goes out, so if your display drains down 2" you have a mess. That's not considering the water in your plumbing that will drain back or whats in your skimmer or reactors.

I am a master of water on the floor Gerwin, trust me on these things!

yes but when set up by a master you should only drop 1/2 inch =2.5 gallons, as a mistake you go to 1" then 5gallons still giving you 5 to spare. I appreciate what you are saying though but most of the overflow problems that occur from faulty setup design would probably overflow a 55 gallon tank down below.

[C-21 USAF]

Gerwin's got a point...my 150 only drains about 1/2" and I designed it that way...of course you could have more or less if you wanted it.

Phisher has great situational awareness when it comes to designing a system and how much space is needed

[phisher]

Ha mine only drops about an inch as well because I had to use a 20g sump!

Just before leaving for MACNA I did a water change, before turning off the pump I was doing something in the tank and pushed one of the loc-line nozzles down an inch or so and didn't realize...needless to say I shut the tank off and turned around for a minute...next thing I knew my feed were wet. Needless to say I like a little safety margin.

Wife and I were looking at the tiered "0 Edge" tanks at MACNA with the cascading waterfalls...she said, "don't even think about that you spill waaaay to much water already."

[Gerwin]

those things were awesome looking but think you would have to clean 2 sides of your viewing panes