Two Speed Pump - Pump Basket Water Level Drops on Low???

jobondur

Well-known member
Dec 13, 2009
182
Virginia Beach, VA
I've got a Pentair 340042 SuperFlo High Performance Energy Efficient Two Speed Pool Pump, 1 Horsepower, 230 Volt, 1 Phase pool pump. When I run it on high, the strainer basket fills up and maintains a full level. But when I switch it over to low, the water level eventually drops to below the level of the water inlet. It's obviously not starving for water and I ran it that way all last year, but I'm wondering if this is normal. Anybody have any input on if this is normal. And if not, what's going on and how do I fix it?

Thanks....
 

Texas Splash

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When you run it on high, I'm assuming there are no air bubbles in the pump basket or from the return jets correct? If there are, that would be an indication of a suction side air leak. In fact, sometimes an air leak can present itself in a sutble way when the suction pressure is low, but then when you crank it up on high the suction tightens the gaskets on some areas. A good example is the pump basket (clear lid) O-ring. So I would first rule-out any potantial air leaks on the suction side and make sure all those O-rings are lubed well.

After that, in my 2-speed pump, the water level begins to drop (on low speed only) when my filter is getting dirty. That's my first clue to get out there and rinse my cartridge. So if you have any excessive backpressure from a dirty filter, that could also be part of the issue. Someting to consider either way. Let us know how it goes.
 

Jimrahbe

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Jul 7, 2014
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jo,

I would assume a small air leak. I would look at the O-Ring under the pump lid.. At high speed there is a lot of suction that sucks the lid into place.. At low speed there is not as much suction and a little air can enter around the O-Ring. I say that knowing that the Pentair lid is one of the better designs, but that is where I would start..

When you shut off the pump, does water show up anywhere?

Thanks,

Jim R
 

jobondur

Well-known member
Dec 13, 2009
182
Virginia Beach, VA
When you run it on high, I'm assuming there are no air bubbles in the pump basket or from the return jets correct?

That's correct. When running on high, there are no air bubbles.

When you shut off the pump, does water show up anywhere?

Water doesn't show up anywhere that I've really noticed. I'll inspect better when I get home.

I'll open up the pump basket and clean out the debris when I get home. I'll then clean the lid and flange surface really well and lube the o-ring before re-installing the lid and see if that helps. One thing I've noticed with that lid is that to get it truly on all the way, I literally have to hit it with a mallet (which I do). That thing does not go on easily at all. I'll then run it on high until the basket is full and turn off the pump for a while (over night possibly) and then go out and see if the water level has dropped prior to turning the pump back on.
 

Texas Splash

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One thing I've noticed with that lid is that to get it truly on all the way, I literally have to hit it with a mallet (which I do).
I have to do that to remove mine. Some lubes are better than others, but it's good to check. And if nothing changes after messing with items at the pump or suction lines, make sure the filter isn't dirty.
 

jobondur

Well-known member
Dec 13, 2009
182
Virginia Beach, VA
If the problem still exists after doing the above, what are the other likely culprits of the suction side leak? And exactly what is meant by "suction side leak"? What parts of the system are encompassed by that???
 

Texas Splash

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That's what I thought but then the talk about the filter being in the mix confused me. So if the leak's not in the pump, then I've got some major issues because everything else is underground....
Don't let that get you too side-tracked. I only asked becasue it happens to me personally. A dirty filter means nowhere for water to go, so it backs-up and my pump basket water level drops on low speed. Plus, it's a relatively easy thing to check/do - at least for me. But focus on the suction side first to ensure everything is air-tight. If it appears to be, then you might check the filter to ensure it's not dirty already, and make note of the pressure gauge to see how quickly it rises.
 

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duraleigh

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Apr 1, 2007
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One thing I've noticed with that lid is that to get it truly on all the way, I literally have to hit it with a mallet (which I do).
That is bad practice, A properly seated and fitted O-ring will seal that junction completely when the pump is running.

You don't even have to tighten the lid......suction from the pump pulls the O-ring into place and you should not have to tighten the lid other than hand tight.......and even then, just barely hand tight.

You may need a new or different O-ring (or lid or pump basket) but striking the lid with a mallet only causes more issues.
 

jobondur

Well-known member
Dec 13, 2009
182
Virginia Beach, VA
That is bad practice, A properly seated and fitted O-ring will seal that junction completely when the pump is running.

You don't even have to tighten the lid......suction from the pump pulls the O-ring into place and you should not have to tighten the lid other than hand tight.......and even then, just barely hand tight.

You may need a new or different O-ring (or lid or pump basket) but striking the lid with a mallet only causes more issues.

I don't hit it to get it to create a better seal, I hit it because the lid is designed to turn until the ears are perpendicular to the pump housing when fully closed (i.e. that's when it hits the lid stops molded into the plastic). I've honestly never tried to just hand tighten it and see if that's sealed enough. I just always assumed it needs to be completely turned.

And BTW, the lid stops turning (hand tight) when it's about 30 degrees from being completely perpendicular. I'll try it your way tonight and see what happens.
 

duraleigh

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Good! I am pretty sure it will work for you and, while not quite lined up, it is a much easier (and potentially less damaging) approach. Let us know what you find.

I'm curious......if you leave the pump off for more than an hour, does the water start to drain from the pump basket......slowly?

Oops! I see you have plans to address that....sorry.
 

jobondur

Well-known member
Dec 13, 2009
182
Virginia Beach, VA
Got home and took the lid off and lo and behold, the basket lid gasket was pinched. I straightened it out, lubed it up and closed the lid and it was definitely better. But I did go ahead and order a new one off Amazon since it was ripped a little in that section. Now that it's lubed and not pinched, the lid goes on pretty easily by hand (go figure)….

Also, decided to check the O-rings in my filter relief valve and when I took it apart they fell out in pieces. So I ordered some of them as well. So I'm running filterless for now.
 

Texas Splash

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Got home and took the lid off and lo and behold, the basket lid gasket was pinched.
Also, decided to check the O-rings in my filter relief valve and when I took it apart they fell out in pieces.

Alright!

full
 
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