poolpartyofsix

New member
Jul 5, 2021
3
Raleigh, NC
Pool Size
35000
Surface
Vinyl
SWG Type
Pentair Intellichlor IC-60
My filter and pump sit about 40’ from the pool and slightly uphill. I lose prime the moment I switch the valve to backwash. Is there an alternative way to backwash?

Pentair Tagelus 100, Pentair VSP
Pump, 2” plumbing, 35k gallon pool - installed this year.

-side note: to prime the pump I have to close one skimmer, and use a pvc pipe in the other skimmer filled with hose water to ‘level out’ the pool water from the waterline to the pump. At the moment I turn on the pump I have to remove the pvc pipe. It’s cumbersome but it works.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
14,827
Pleasanton, CA
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
How much higher is the pump than the pool water?

Is there a check valve or regular valve right in front of the pump suction?

Does the pump lose prime when it is off?

Have you tried switching to backwash with the pump running?
 

poolpartyofsix

New member
Jul 5, 2021
3
Raleigh, NC
Pool Size
35000
Surface
Vinyl
SWG Type
Pentair Intellichlor IC-60
It’s a very gradual slope, might be 3-4’ higher but I haven’t checked with a string level to measure.

The pump does not lose prime when the pump is off.

I lose prime when switching the valve to backwash even if pump is running.

I did not put a check valve in front of the pump. I was afraid of it getting clogged and causing problems, but there is room to add one if that is recommended.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
14,827
Pleasanton, CA
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
3'-4' is not too bad so it shouldn't be that hard to prime. Given the pump loses prime when switching over to backwash makes me think there might be an air leak in the system. Backwash mode generally has less head loss than filter mode so flow rate goes up, suction goes up and it is more likely that an air leak will happen. The hard part is finding where it might be. Normal suspects are the pump lid gasket and the drain plugs. A little pool lube there might help.

In normal filter mode, is there any air in the pump basket?
 

poolpartyofsix

New member
Jul 5, 2021
3
Raleigh, NC
Pool Size
35000
Surface
Vinyl
SWG Type
Pentair Intellichlor IC-60
I’ll try that now.

I can’t even move the valve handle without losing prime. The moment I push it down to move it, the basket empties.

in normal pump mode, when it’s priming the basket of full of water and as long as the pump is at a higher speed, it’s totally full of water. As it settles in to a lower speed there’s a little bubble of water at the top of the pump basket.
 
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