Pump losing prime overnight

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ellsbird
Pool Newbie
Pool Newbie
Posts: 2
Joined: Mon 25 Jul, 2011 10:39
My Pool: 10k gallons, in ground, gunite/diamond brite, Pentair Whisperflo pump and Pentair cartridge fliter
Location: Orlando

Pump losing prime overnight

Postby ellsbird » Mon 25 Jul, 2011 10:56

Please help me with ideas as to how I am losing prime overnight - it's making me crazy and I'm sure it should be simple.

Here's the situation:
In ground pool, spa, cartridge filter, gas heater, salt cell
1. pool operates on vacuum and skimmers mix all day. Main drain is off.
2. overnight, pump loses prime
3. when pump first shuts off, all is silent and good. About 15 minutes later, can hear a little glugging in the filter housing. After a several hours, all water will be drained back into pool ( I assume - but pump loses prime).
4. No visible water coming from equipment area
5. The only way to keep prime overnight is to turn valves exlusively to spa function. Not sure if this indicates something exclusive to pool line, or is just a pressure thing.
6. I have tested turning each of the pool functions off individually (skimmer, vac, main drain) and has no effect.
7. Have replaced filter housing o ring and need to replace the pump basket lid o-ring 0 just got the wrong size; however I don't really think it's from there as usually I can see air bubbles immediately if there is a little leak there.
8. I don't think I'm losing water underground - seems my pool level is OK.
9. When pump first comes on, a little air comes out, but after, runs fine. If I were to leave the valves on pool function, eventually pump would prime, so whatever it is, isn't enough to keep pump from priming, but enough to break vacuum overnight!

I am at a loss! Whatever it is I think is very small as it doesn't take effect right away. We have tried applying soap to the fittings and can't see any obvioud air being sucked in.

Thanks!!


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mas985
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Posts: 199
Joined: Tue 08 Sep, 2009 10:40
Location: Pleasanton, CA, USA

Pump losing prime overnight

Postby mas985 » Mon 25 Jul, 2011 14:51

Sounds like a tough problem.

When you hear the gurggling in the filter, is there any air in the pump basket? If not, then the air may be coming from the pressure side of the pump. Sometimes small leaks will seal while the pump is on but when off, they will allow air into the filter. Did you also repace the o-ring for the bleeder valve at top of the filter? Otherwise it could be the valve that switches between the spa and pool.
Mark
Hydraulics 101 ; Pump and Pool Spreadsheets ; Pump Ed 101
18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, Solar Panels, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater
ellsbird
Pool Newbie
Pool Newbie
Posts: 2
Joined: Mon 25 Jul, 2011 10:39
My Pool: 10k gallons, in ground, gunite/diamond brite, Pentair Whisperflo pump and Pentair cartridge fliter
Location: Orlando

Pump losing prime overnight

Postby ellsbird » Tue 26 Jul, 2011 12:41

No air in the pump basket. I have not replaced the o-ring in the bleeder valve, but we could try that as well. I am just perplexed as to why it stops when on spa only - if it were something like that (flow goes through filter regardless). Also, I don't hear any sound coming from the bleeder valve when closed.
czechmate
Swimming Pool Superstar
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Posts: 401
Joined: Sat 16 May, 2009 09:20
My Pool: 16 x 32 gunite21000 gal., Diamond Brite Blue, Swimquip XL pump, DE36
Location: Texas

Pump losing prime overnight

Postby czechmate » Sat 30 Jul, 2011 06:19

You most likely have very small leak in the backwash valve or filter can rubber seal.
Air creaps in the filter dome overnight. Sometimes it is the cover on the pump strainer.
Air in the pump basket can only be sucked in from the skimmers, due to a low level, leaves obstruction in the skimmer, stuck flap, etc.

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