Swimming Pool & Spa Construction & Maintenance/back pressure when turning off pump


I have a 20X50 in ground rectangular concrete pool, 9 ft deep with a salt chlorinator. Two skimmers and one doesn't seem to have as much suction as normal. When I turn the normal one off at the valve, it pulls water but only half as much as it used to. When I turn the pump off there is back pressure and water actually blows the skimmer lid off of the one that works normal. Is the other line partially stopped up or is there another problem? I live in Oklahoma. Water is crystal clear and does not seem to be loosing water. Pump system and sand filter are on their 2nd season but the pool is about 15 years old with PVC pipe (as far as I know).

Hi David,

Thanks for your question.

It sounds as if the filter is getting some air into the skimmer that is not pulling. Your problem could be more in the valve as opposed to the skimmer itself. What you describe as the lid blowing off is really common when excess air is present in that particular line.

If that particular skimmer that is giving you trouble is further away from the pump, it will naturally draw less water (closer to the pump = more action/flow, further from pump = less action/flow).

I would recommend operating the pool with just the troublesome skimmer only for a couple of days to see what happens... It's going to be a matter of trial & error.

I'm sorry that I can't be more helpful. Let me know.

Swimming Pool & Spa Construction & Maintenance

All Answers

Answers by Expert:

Ask Experts


Ron Parrs


Swimming Pool & Spa/Hot tub care. Water chemistry. Problem solving. Residential pools, vinyl liner a specialty. Limited knowledge of gunite or plaster pool construction. Familiar with almost all types of sanitizing systems whether chlorine, bromine, salt, low & non-chlorine chemical treatment, biguanide (Baquacil or Soft Swim), Nature2, etc. Experience treating bio films in pools and spas. Aqua finesse, PoolNaturally & SpaNaturally (using sphagnum moss to control pool & hot tub chemistry & bio-films).


Pool & spa care experience for over 37 years. Owner of Par Pool & Spa in Stratford, CT. Websites: www.parpools.com , www.spacareonline.com , www.pool-care.net , www.parpoolsblog.com

EzineArticles.com , websites mentioned above, Pool & Spa News

BS Accounting, University of Bridgeport, almost yearly participation in BioGuard Pool Schools, BioGuard University, Chem Plus Schools, Chem College attendance since 1981

Awards and Honors
Past President - Connecticut Spa & Pool Association, Past Board Member - Northeast Spa & Pool Association

Past/Present Clients
too many to answer

©2017 About.com. All rights reserved.