Losing pressure in filter

[rmace32]

I had a new sand filter installed this year and have nothing but problems. The filter I have is a Pentair Triton II side mount TR100 sand filter. I have sand and glass installed in the filter.

I started off with having sand in the pool and a lot of it. I found that problem as it was missing the strainer on the air relief tube. This was replaced and no more sand in the pool.

I then noticed when running the filter continuously (over night when I shock the pool), the next day the pressure in the filter has dropped significantly. The normal start up pressure is about 15 psi and the day after running the filter it is down to about 5psi. I located a crack in the plumbing from the heater to the pool and that has since been repaired. I thought this would fix the pressure problem but it has not.

I turned the filter on after the pipe repair and after about 6 hours the pressure went from 15 to 10psi.

I am extremely frustrated at this point. Any thoughts on what’s causing the pressure to fall? The only other thing I can think of is possibly low on sand from when I was losing it in the pool. Would having low sand cause the pressure to gradually fall or would it always be low from when I first turn it on?

Please help.

 

[rmace32]

I had a new sand filter installed this year and have nothing but problems. The filter I have is a Pentair Triton II side mount TR100 sand filter. I have sand and glass installed in the filter.

I started off with having sand in the pool and a lot of it. I found that problem as it was missing the strainer on the air relief tube. This was replaced and no more sand in the pool.

I then noticed when running the filter continuously (over night when I shock the pool), the next day the pressure in the filter has dropped significantly. The normal start up pressure is about 15 psi and the day after running the filter it is down to about 5psi. I located a crack in the plumbing from the heater to the pool and that has since been repaired. I thought this would fix the pressure problem but it has not.

I turned the filter on after the pipe repair and after about 6 hours the pressure went from 15 to 10psi.

I am extremely frustrated at this point. Any thoughts on what’s causing the pressure to fall? The only other thing I can think of is possibly low on sand from when I was losing it in the pool. Would having low sand cause the pressure to gradually fall or would it always be low from when I first turn it on?

Please help.

Also it is an in ground pool and the water is very cloudy.

 

[JohnT]

Welcome to TFP!

Sorry you’re having this headache. A likely problem is water flow into the pump dropping. The gauge essentially measures how hard it is to push water through the filter. Pushing less water takes less effort, so the pressure goes down.

Does the pump basket stay full? Anything odd happening in the skimmer(s)?

What pump do you have?

 

[rmace32]

I have a Pentair SuperFlo 1.5hp pump. The pump is newer I just got it last year. The skimmer baskets are clear and have been while getting the pressure drop. Another thing I have tried was the impeller on the pump. I spun this with a screwdriver and it didn’t feel obstructed.

 

[JohnT]

What happens if you run with the filter on recirculate?

 

[rmace32]

I have a push pull valve on the filter so I don’t have that option. It’s just filter or backwash.

 

[rmace32]

What happens if you run with the filter on recirculate?

Shoot. Now that you mention that, reminded me of something I believe is super relevant but I have no idea what it means.

Prior to installing the new sand filter I had an old DE filter. I was having the same issue with low water pressure returning to the pool. If I ran the filter, after a few hours it was barely blowing any water back into the pool.

I was having to bypass the filter and run it on recirculate and the water flow was fine while in recirculate. What does this mean???

 

[JohnT]

Shoot. Now that you mention that, reminded me of something I believe is super relevant but I have no idea what it means.

Prior to installing the new sand filter I had an old DE filter. I was having the same issue with low water pressure returning to the pool. If I ran the filter, after a few hours it was barely blowing any water back into the pool.

I was having to bypass the filter and run it on recirculate and the water flow was fine while in recirculate. What does this mean???

Can you run on main drain or skimmer only?

 

[PoolStored]

I was having to bypass the filter and run it on recirculate and the water flow was fine while in recirculate. What does this mean???

and the water is very cloudy.

It means you have organics in the water and need to SLAM. Lower return flow is almost always organics. It doesn't explain the filter pressure gauge.

How are you testing your water? If you don't have your own kit, order one now. Link-->Test Kits Compared

If you pool is cloudy, you should follow the SLAM process. We will figure out the filter later. Link-->SLAM Process

Does the gauge go to 0 when you turn the pump off?

 

[Texas Splash]

Keep in mind a weak or low filter pressure is different than weak pressure at the return jets. As PS noted, weak pressure at the return jets is usually accompanied by high pressure at the filter from organics overloading the filter. That would make sense especially with the DE.

As for the original issue of low pressure now, two things come to my mind. Bad pressure gauge which might be confirmed by odd behavior of the needle and good water pressure at the jets. The other perhaps a partial blockage in the suction line.

 

[rmace32]

Can you run on main drain or skimmer only?

Yes I have shut off valves on two skimmers and the main drain

 

[rmace32]

Keep in mind a weak or low filter pressure is different than weak pressure at the return jets. As PS noted, weak pressure at the return jets is usually accompanied by high pressure at the filter from organics overloading the filter. That would make sense especially with the DE.

As for the original issue of low pressure now, two things come to my mind. Bad pressure gauge which might be confirmed by odd behavior of the needle and good water pressure at the jets. The other perhaps a partial blockage in the suction line.

So when I had the sand in the pool, I sucked a lot of it up into the skimmer. Could sand be sitting in the suction line?

The pump stays primed, I’ve never had an issue with that. And the gauge goes to zero immediately when shut off so I feel like the gauge is fine. I have noticed when the pressure in the filter drops so does the water flow from the return jet.

 

[JohnT]

I would try operating with each of the water sources shut off one at a time. And see what the pressures are. Maybe something is in a line that moves during pump operation.

 

[Mayorb]

1. Good flow while in recirculate mode.
2. Sand returning to pool, low PSI in filter mode.
3 No problem priming.
So #1 and #3 eliminate a pump issue.
The ONLY way sand would get out of the filter and into the pool is a broken lateral(s). I deep clean sand filters with the top of the filter completely removed while system is running in backwash mode, meaning much higher GPM rate than when in normal filter mode. That removes all the back pressure from the rest of the system downstream, and the sand never gets up to the diffuser on top of the internals, nor above the air-relief tube (assuming it is properly connected).
Having said that, I have no experience with glass media.
But I am never too old to learn, and I'd be interested to know how otherwise, sand could return to the pool.