Help - Sand filter building pressure quick after replacing sand.

[Grahamwho]

So just bought a house with a pool, last owners say it hadn’t wasn’t used last season but I wonder if it’s more.
water was like coffee to start but have thrown all kinds of chemicals at it.
Anyhow my current problem is we decided to change the sand, after putting the new sand in the pressure seems to rise from 17-18 psi at start after backwash to 22-24 within a couple of hours and then within 3 or 4 hours it can be as high as 35+ psi, this doesn’t seem right to me, the water is cloudy and I’m sure there’s lots of cleaning to do but the pressure shouldn’t be rising that fast should it. This did not happen with the old sand. The old sand also started at around 17-18 psi, but I don’t think it would have got to 35 psi in a week.

The sand is the hth pool filter sand from ace hardware, the filter is a Hayward s-210s. The pump is what I believe to be an old Hayward 1.5hp super II, with an aftermarket 1.5hp motor as best I can tell. Thanks in advance for any help you can give!

 

[Bama Rambler]

It's most likely doing exactly what it's supposed to be doing. Catching debris.
The old sand was probably channeled and the debris was bypassing it. A good deep cleaning may have helped, but you've already replaced it, so now to get serious with cleaning the pool. Read about our SLAM Process and you'll have a better understanding of what you should be doing to clear up the water.