Sudden loss of pressure on pool opening this year

[nikolasmor]

Hiya \o

I have a 16x32 IG with a SWG, Pentair Pump and S220T sand filter. I was away last week and asked the kids to scoop leaves for me while I was gone so that the Doheny Discovery I ordered didn't get overwhelmed when I put him in after returning. I noticed the low pressure light on the SWG was on upon my return and so I backwashed like normal, rinsed, and the put it back on filter mode. Went out to watch the new toy run while I skimmed and scooped. 30 minutes later the light was on again. Skimmer was clean and the basket before the pump was clean also. I replaced all the sand at the end of last season because I had a lateral break. I backwashed again and it was fine for about 20 minutes before the light came on again.

I opened the lines and checked the pump impeller thinking something might be clogging it, but it looked perfect When I primed I could see a few leaves swirl in the pre-pump basket but not much at all. My pressure gauge is rusted (new from last year) so I can't see the pressure. A new one will be here tomorrow with a 90* angle to keep water from filling in it. I also ordered a medium hose bladder to attach to the hose and attempt to "pressure" any blockages out that may exist from the skimmer to the pump.

The water flows heavy on backwash and rinse.

I plan to take the shop-vac to it tonight and blow from the pump side back towards the skimmer.

Any other thoughts on what I should be doing or looking for to get rid of this low pressure?

 

[faby3003]

Do you have a full set of test results? How does your water look? Are you experiencing weak flow from your returns? Does backwashing make the flow from your returns stronger? You could be fighting algae and quickly clogging your filter.

 

[nikolasmor]

Do you have a full set of test results? How does your water look? Are you experiencing weak flow from your returns? Does backwashing make the flow from your returns stronger? You could be fighting algae and quickly clogging your filter.

Full results are at home, I'm going through the SLAM process now but came out of winter with about a 20 CYA and and socking the 12 lbs of CYA now (almost all dissolved) I know it'll take a few days to show up. Pull has no green in it but I can't see more than about 6 feet into it very clearly. Ph was off the charts (over 8) and FC was very high from the bleach. Salt is at optimum level and water temp was 78*.

Weak flow out of returns and into skimmer, backwashing increases the flow temporarily (up to 15 minutes at the most) Algae would clog up a sand filter the same as a traditional? I'm always learning

 

[faby3003]

If your pool is cloudy then I would blame that versus an equipment issue. I don't have experience with sand filters, but I would assume they can clog quickly just like other filters.

Also, I have had CYA clog my filter. I think the CYA dissolves into smaller particles in the sock, but these particles are still big enough to get caught on your filter. So they can cause filter pressure rise until they fully dissolve.

 

[nikolasmor]

Roger that, it was an issue before adding the CYA, so certainly didn't help. Impeller looks fine and the sand was new, I'll get the pool nice and clear before doing anything drastic. Can't hurt to try and clear it out with a hose bladder from pump to skimmer side tonight. #1 Goal is to get the pool clear and all levels as they should be, then go from there.