Pump Loosing Prime issue

luckyc1423

Well-known member
Apr 8, 2017
163
houston texas
Newly installed pool and pump. for the first two-three days the pump primed and stayed prime the entire time.

Today i noticed the pump had no water in it so it lost its prime and i shut it off. i then restarted it and it primed without issue but 2 hours later lost the prime again and the pump basket was half full of water. just shut it off and restarted and it primed no problem but the basket will start to go to half full in the pump.

You can see water coming into the pump basket. but its only half full.

any ideas why a pump would have no issues priming, but the basket not be full of water several hours later?
 

luckyc1423

Well-known member
Apr 8, 2017
163
houston texas
quick update.

I just turned it off adn restarted. the pump primes flawlessly and primes at 3,400 rpm's

once the prime stage is over pump goes to 1,800 rpm's. within 20 minutes pump basket is half full of water.

I increased rpm's to 2,500 to see if water would fill back it (prime again) and it does. so at higher rpm's everything seems to be working correctly.

what would be happening at the lower rpm range?

*one extra note. at lower rpm's on occassion we would see air bubbles slowly coming out of 2 of the 6 returns. so i am assuming at lower rpm's i am letting air in somewhere, but why wouldnt the same issue happen at higher rpm's?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,308
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Check, clean, and lube the pump basket cover gasket and the drain plug orings. Depending on pump, there is likely two drain plugs on the pump body.

 

luckyc1423

Well-known member
Apr 8, 2017
163
houston texas
Thank you I’ll do that tomorrow and see.
It’s a Pentair variable speed pump 011056

Your thinking at lower rpm’s it’s letting air in the system?

What wouldn’t that happen at higher rpm’s?
 

luckyc1423

Well-known member
Apr 8, 2017
163
houston texas
Additionally, check your water level and make sure you're weir door is not stuck in the closed position.
I thoight Of that and just had water come in from floor drain snd the basket wouldn’t fill back up. So not specific to the skimmer.

Just weird if it’s a air intake issue that it would happen only at lower rpm
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,308
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
There is less suction head at low rpm.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,308
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
At low rpm. the lessened suction head does not pull the pump basket lid down against the gasket as much. If lubricated and clean, that should not be an issue. Try cleaning and lubricating the gasket and sealing surfaces. Be sure to use a proper Pool Lube as described in the article linked above.
 

luckyc1423

Well-known member
Apr 8, 2017
163
houston texas
Gotcha. I am out of town going to try this tonight when i get Home.
My wife has been messing with it. At 2,500 rpm’s it almost stayed completely full of water all night long. Maybe 1” of air ok the top of basket so still slowly letting air in at the higher rpm
 

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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,308
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
VS pumps can build a small air bubble at low rpm for extended periods. But 2500 rpm is not low. 1200 rpm or slower is low.
 

luckyc1423

Well-known member
Apr 8, 2017
163
houston texas
Ok here is the latest update. Everything started working fine on its own. We had leak detection come out to make sure there was no leaks and of course there was no air bubbles happening at the time they came out (that was 2 weeks ago).

in the last 2 weeks everything worked flawlessly up until today.

Today we turned the pump on (50% main drain 50% skimmer - only have 1 skimmer) and the pump would not prime and pump full of air.

We turned it to main drain only - pumped primed awesome adn runs perfectly.

So it seems like a skimmer issue.

We turned to skimmer only and nothing.
Tried skimmer only again and we put our hand over the skimmer hole to force suction and slowly you could start to feel presure on your hand. we released our hand and the skimmer started to suck water but the problem is, it is sucking water at a much faster rate than the pool can keep water in the skimmer basket so the skimmer basket runs dry.

We repeated the above step with a water hose in the skimmer basket and the skimmer basket still ran dry.

Water level is right where it needs to be (midway up the skimmer basket).

Pool has 1 main drain 1 skimmer
Pool is small, 220 sf, maybe 6,000 gallons.

any idea why the skimmer wont suck? any idea how the skimmer basket can go dry i figured the pool would always keep water in it if water level is right?

Questions/thoughts:
1) maybe since the pool size is small, i need to do 75% main drain 25% skimmer and leave it at that?
2) should i reduce prime rpm's? thinking prime rpm's are to high for skimmer only.


again at 50/50 main drain to skimmer split it had been working, but not working today.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,308
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
It sounds like your weir door in the skimmer is sticking closed. If the water level is correct in the pool, that is the only way the water would be restricted for entry into the skimmer body.
 

luckyc1423

Well-known member
Apr 8, 2017
163
houston texas
It sounds like your weir door in the skimmer is sticking closed. If the water level is correct in the pool, that is the only way the water would be restricted for entry into the skimmer body.

We do not have a weir door we left ours off.
Water halfway up skimmer opening.

1) do you think it’s a clogged line which prevents it from primiminf correctly?

2) is it a air bubble?

3) does the line go dry completely which is why water comes our so quick once we stick our hand over it?

As everything been priming and working great. Water level perfect
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,308
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Not sure why you would leave the weir door off -----------

I would put the weir door back on. You may find that resolves it.

What pump do you have? If a VS pump, reduce the rpm setting for priming.
 

Danimal92Sport

Well-known member
Jul 5, 2017
139
Southern Indiana
Pool Size
4600
Surface
Fiberglass
Chlorine
Salt Water Generator
A 3hp pump paired with low restriction on the return side can probably flow more water than a single skimmer can provide unless the water level is pretty high on the skimmer. In my case, a 1.88hp VS pump at full speed with 4 returns and a big cartridge filter (low restriction) will suck my single skimmer dry unless the water level is at the TOP of the skimmer. Therefore, I have limited the max speed of the pump way down to 1800 rpm to avoid the risk of running the pump dry. Most of the time, my pump runs at like 900rpm, but will only prime at 1800.

My advice would be to mix the bottom drain back in with the skimmer on the suction side, and reduce the max speed of the pump down, and consider running at a speed lower than max (after priming) that still gives good skimming, is sufficient for your heater and salt cell if you have them.
 

markayash

Gold Supporter
Mar 21, 2016
3,544
Atlanta Ga
We do not have a weir door we left ours off.
Water halfway up skimmer opening.

1) do you think it’s a clogged line which prevents it from primiminf correctly?

2) is it a air bubble?

3) does the line go dry completely which is why water comes our so quick once we stick our hand over it?

As everything been priming and working great. Water level perfect
When your pulling from the skimmer have you watched it and made sure it’s not sucking air?
Could be a clogged return, I have used a shop vac in the skimmer line inside the skimmer to unclogged them. Sometimes leaf’s and acorns clog mine. If it’s clogged it won’t take but a few seconds to pull it back out.