Pool: suction side leak?


Old 09-23-19, 12:39 PM
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Pool: suction side leak?

have an old Anthony gunite/plaster pool. So 2 seasons ago, suddenly during the season, the pump seemed to be sucking in air. the strainer basket would get only half full of water, the pressure on the filter essentially non-existent. it was flowing water, but the pressure out of returns was low and suction low. The pool was leaking badly and needed complete renovation of the beam/ coping. It was started last season and finished this season. So when started pump, same issue. there doesn't appear to be any water leakage as I think I only added about an inch of water since it was opened in July. I have a one -way valve right before suction line enters pump, And the pump is always primed when I start it up. If I had a leak in the suction line, I would suspect I would lose prime. The pump doesn't have a continuous tone when running. It sounds like speeding up then slowing down-like it just sucked in some air. and no pressure on filter. But my pool has been clean all season. no algae buildup, no DE in the pool (holes in filter panels would account for low pressure but not the low flow/suction coming from returns)

some details. I have super II pump about 10 years old. threre is 2" suction line coming in. I have two skimmers. One has never worked since we bought the house. I have always left the plug in it. It is skimmer only. The other skimmer is combined skimmer/main drain. But many years ago I diagnosed a leak in the flex pipe running from the skimmer down to main drain. I left bottom plug in the skimmer (blocking the hole to drain, but the line from skimmer to the pump is still fully open). I also plugged the main drain (using scuba equipment) That solved the leak and the pump ran fine at that time, even though water only coming from the (I think)) 1" line from the one skimmer. then this problem happened suddenly mid season. I mention this cause I have read elsewhere that closing the inlet valve to limit amount of water available to pump can mimic the symptoms I have. so while not due to only having one skimmer functional (since it has worked fine with only 1 skimmer in past), could a blockage in the one skimmer line be limiting flow that pump can't get enough water?

SEveral years ago the lines were leak tested. none were found. the shell was the leak and that is now fixed. I have pulled pump apart to check impeller for debris or any obvious problems, but found none. I sprayed suds around one way valve and pipe coming into pump, as well as the pump/cover itself but didn't find anything., Lid O ring good and lubed up and lid tight. if the pump seal were bad, wouldn't I expect to see water leaking from bottom of pump?

any thought appreciated. leak detection company has min $675! And I'm not sure I have leak since not adding water and always primed. pump seal? obstruction in an already compromised system using only 1 skimmer?

oh, forgot to mention that there is steady stream of air bubbles coming from return lines and when open the outlet on top of filter, water doesn't even come out-I guess draining out into return line too fast to build up any pressure. I even blew air hose to make sure DE not blocking things up.
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Old 09-23-19, 04:05 PM
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I have an old Sylvan pool. Approx 45 years old. Sylvan and Anthony were competing companies back then. The biggest difference between the two is the actual pool construction. Anthony used Gunite and Sylvan, I believe, used concrete under pressure and then a plaster covering.

You should have two skimmers and two bottom drains. There should be two valves at the pump to select which one or both is active. If you put a plug in the bottom of the skimmer...... just the bottom drain is on. If you drop a piece of pipe..... roughly a foot ...... into the skimmer hole..... it shuts off the bottom drain and just the skimmer is on. This is how my pool is setup and so are most others that I've seen.

All suction and return lines should be 1-1/4" or 1-1/2". My lines are all 1-1/2".

If you have a lot of air bubbles in the return..... you are drawing air in on the suction side. An impeller issue could cause lack of waterflow but not air bubbles. If you didn't properly winterize your lines.... one could be cracked. It could allow air in without a major loss of water.
Old 09-23-19, 09:46 PM
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any cheap way to pressure test lines? Can't seem to find exactly what I would need. I could make something I guess or pay $500-$700! just would be nice to find device made to test lines that wasn't too expensive. just air or hose fitting, pressure gauge, and way to attach to lines either rubber stopper or maybe thread into skimmer, which is 1.5" thread.

some more background-purchased house in 1999. pool built in 70's. since we have been here, it never had two drains, only one in deep end. and never had any valves near pump to adjust which skimmers are active. there is threaded plastic insert (skimmer diverter) in each skimmer that you twist to adjust suction in THAT skimmer between skim/drain. the two lines from the skimmers join under the concrete to form a single 2" line. you are probably correct that they are 1.25 or 1.5". I can't see them at all, just tried to estimate based on size of opening I see deep inside skimmers.

the skimmers are not exactly like yours. there is large hole in bottom (1.5" threaded opening). then about 2" below the bottom of skimmer is a hole pointing 90degrees from the face of the weir door. That is the line to the pump. Straight down that large hole is the line going to the drain, at least in deep end. The shallow skimmer has plastic plug below the line exiting to the side. So if put the large plug in bottom of skimmer, as you describe the pump will pull from drain. but mine has another plug that goes in first when winterizing. it is smaller and goes through the big hole in bottom of skimmer and past the side opening to block only the line going to the drain. the plug has a extension on the top so that you can reach the wing nut to tighten it up and place/remove it. no pipe needed and no where near a foot.

now the shallow skimmer never worked. when first moved in I tried using air pressure in reverse in case of a blockage but it didn't work. I also didn't detect any leak, at least no leak under atmospheric pressure. with water pool level below the skimmer, I lower water level in skimmer to level of the large hole in bottom. days later the water level didn't change. That was a long time ago. I just looked at the line with cheap scope cam and couldn't even get it far into hole as line appears to be like a clogged artery and closed off. the concrete around this skimmer is different so leads me to believe they had issues with it in past. I think maybe they replaced a section of pipe with flex and that has gone bad. I have heard that putting chlorine in skimmer can damage flex. the chlorine levels build up when pump is off and it eats at the flex. and putting chlorine in skimmer is what we were told to do.

the main drain off of deep side skimmer had a leak in the line. I diagnosed same way checked other skimmer but also I put a plug in the main drain inside the pool. then with pool water level below skimmer and then lowering the water level inside skimmer to just below the line going to the pump, I noted that the water inside the line going to main drain dropped. only place for it to go, since the main drain inside pool plugged, was a leak. visible was flex line and it had same clogged artery appearance and would collapse if applied too much suction, which was adjustable with a plastic insert inserted into the big hole in bottom of skimmer. one way it would block off line to main drain. as rotate it would add in more suction to main drain. if added too much, then line would close. So that is why eliminated the main drain completely. when did renovation, they covered it. I didn't want to deal with replacing that line, not knowing how far down it was bad.

improper winterizing is unlikely as I always did it myself. I would lower water below returns. then for returns blow them out from near filter. then pump in pure propylene glycol pool antifreeze till I would see it coming out all the returns, meaning it had pushed out all the water. Then put in plugs and keep filling with more antifreeze. I think it is -50 protection. don't use variety with isopropyl alcohol since pumping it and it is flammable. for suction side I would also blow out line, but also use shop vac to suck up water pushed into skimmer as pressurizing other side. then I would pump the antifreeze using modified plug I made with hose adapter so I could pump it till started to come out near pump. then I would put antifreeze in skimmers, put in empty plastic jug from antifreeze and hold it down with the skimmer lid, then cover that with another piece of plastic to practically eliminate any water entering skimmer and if it did, the antifreeze would prevent from freezing and if did freeze, the plastic jug would give way to relieve pressure. If anything, this is overkill. but doubt any freezing of lines could occur. And problems started suddenly towards the end of a season. I would think, most likely, that freeze damage would be evident sooner. sure it could be delayed nearly whole season, but I doubt it. I'm hoping that there isn't flex in my one remaining line that has now gone bad!
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