Low Water pressure on the return lines and in the skimmers

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K

kuzya

0
Sep 20, 2013
79
Hi,

I have an issue with the pool in our new house. This is an in-ground pool, irregular shape.
Pentair Challenger pump with Pentair FNSP 60 filter. The pool has two skimmers and one bottom drain.
There are 3 lines going into the filter. 4 lines coming back (3 for return and 1 for water feature).

There is very low pressure on the return lines. I know it should be much stronger. There is also low suction on both skimmers.
Not sure about the bottom drain, it is too cold to test.

The pump primes. There are no water bubbles. There is no pressure gauge, the previous owners plugged the opening on top of the DE filter.
I will purchase the gauge today. Pump works. I checked the strainers at the skimmers and the before the pump and it is clean.

There is a slow leak at the bottom of the impeller housing, probably needs a new gasket.

I had an in-ground pool before with a multi port valve on a sand filter. This filter has a pull up valve that opens on the bottom for backwashing.
I did backwash the filter for 3-4 minutes.

I did close 3 out 4 return lines but the pressure is still low.

Any suggestions on what else to check. I can blow the lines with a vacuum, check the impeller for any blockage.

I did open the DE filter and it looks dirty. Should I clean the grids? and add new DE?

THANK YOU!!!
 
Good. I will post back tomorrow. I will need to buy DE and add it to the filter after washing it. It says FNSP 60 requires 6 lb.
What is the best way to add it to the pool? I have low suction at the skimmer. I think I need to drain the pool before I do this. It has too much
water.

Thanks!!

- - - Updated - - -

One more question. I looked a the large o ring inside the plastic housing where the water is leaking from the bottom.

The o ring looks ok. It is not dry, should I replace it anyway to see if the leak stops?

Thanks!
 
Adding DE thru the skimmer is the way....you'll just have to go slow. Only add aprox 80% of what the device calls for when refilling.

If you feel capable of the task of changing that O ring, I'd say go for it. Rules out the small problems that are easy fixes,right? Don't forget to use the proper pool lube.

Maddie :flower:

Addendum- never drain a vinyl pool below about 18" on the shallow end, or you risk shifting the liner.
 
I feel capable :) I changed it before on a Hayward system.
Looks like you just have to take the clamp off and change the o ring. I am trying to find the correct part.
I am assuming it is called housing gasket.

I have this at home:
Amazon.com : Lube Tube - Pool Gasket Lubricant : Swimming Pool Pump Parts : Garden Outdoor

I didn't know about 80%. Thanks for letting me know.

- - - Updated - - -

I think it is this one. I have a round ring, looks like this.

https://www.amazon.com/Pentair-355329-Front-Housing-Replacement/dp/B0039G4XNW
 
K,

If you disassemble your DE filter and clean it, you need to add 100% of the required DE... You only add 80% of the required amount when you only backwash the filter..

Thanks,

Jim R.
 
I cleaned the filter (it was very dirty) and installed the pressure gauge. I discovered 2 broken grids. I replaced the broken grids with new grids. I didn't put DE in yet. The pressure is between 11 and 12 psi.

I don't have the o ring, it should be here on Tuesday. Pressure is still low. Not enough suction at the skimmers.

What do you think?

Thanks!
 

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K,

It is never a good idea to run a DE filter without DE..

What makes you think there is not enough suction at the skimmers? You may be right, but it would be hard to tell... Are you reaching down under the skimmer basket and feeling the suction or do you expect to see the water swirling around like in a toilet bowl?

The filter pressure is backwards from what you seem to believe... Filter pressure is really the amount of effort it takes to force water through your filter.. lower, in most cases, is better. With a filter pressure of 12 lbs. it sounds to me like your pump and skimmers are just fine. I have a large filter and VS pump... my filter pressure is about 2 lbs. or less, yet I have plenty of water flow.

How about posting a pic of your equipment pad... it would help us help you...

Thanks,

Jim R.
 
K,

So you have three pipes coming into your pump...

I re-read your initial post and see that you have two skimmers and a main drain... I assume that is what the three input valves control.

If all three valves are wide open, then the skimmer that is further away from the pump will have a lot less suction than the skimmer closer to the pump.

As a test, I would open just one skimmer (close the other skimmer and main drain) and feel the suction.. Close that skimmer and open the other one and compare the two. At least that would tell you if either skimmer line is plugged...

If you have a filter pressure of 12, even with no DE, that would seem pretty much normal to me...

If you are comparing this pool with another pool, there are a number of things to remember... All pools are a little different... Different HP pumps, different lengths of plumbing, different sized eyeballs, different number of return lines. Different types of filters. Heaters or no heaters.. etc...

Thanks,

Jim R.
 
The leak is fixed.
Three pipes going into pump.
Two for skimmers and one for bottom drain.
Skimmer further away has less suction if all three are open. I added a lot of chlorine last night. There is a lot of dead algae on the bottom this morning. I will vacuum after work. I had to backwash the filter in the morning. The pressure was 30. Do I need to add more DE after backwashing?
I also want to add CYA. The ph is high, probably because of chlorine. I will do more testing today. I have a kit.
Thank you.
 
K,

After every backwash, you need to add 80% of the amount of DE your filter requires... A pain I know, but the DE is what does the filtering... the grids just hold the DE in place.

Thanks,

Jim R.
 
I added 6 lb yesterday and pressure was around 14. The pump ran for 9 hours and pressure was around 30. I had to backwash in the morning today. Is this normal? The pool was green yesterday when I added DE and chlorine. The color is better today. I need to buy more DE if I have to backwash it this often when the pool is dirty.
Thanks.
 

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