pressure rise with new sand filter

[induce]

just replaced my cartridge filter with a new hayward sand filter. it ran @ 20 psi new and continues to run @ 20 psi after backwashing. everything else seems fine. pool looks great.
it also shows 20 psi when backwashing.....? it does go to 0 when the pump is off. using a Northstar 1.5 hp 2 speed. 22k ig pool.
the cartridge filter ran about 15 psi when clean.
is this too high and do you think there is a install problem?

[JohnT]

The filter itself adds a very small amount of pressure. Something like 0.6psi. Plumbing and valving are the things that cause most of the pressure rise. It shouldn't be a problem assuming you have sufficient flow.

[tenax]

my sta-rite sand filter for reference runs about 17 as the norm..will run as high as high 20's to 30 if i really need a backwash..your manual or on ring on top of the filter likely tells you the maximum rated pressure. for mine, it's about 60 psi..that would be my only concern in terms of what pressure can be handled..can't remember pvc pipe pressure rating but pretty high from what i recall.

[induce]

my guess is that when they took away the old filter and added the big sand filter, they used a couple of 90's to get to the heater and back to the pool.

i replaced the cartridge filter after a muddy water rain deal with our new construction...... straight into the new pool.
it was a pain to clean those cartridges, so thus the change. i'll pick up a new gauge, as i think this is the old one from the old filter.

thanks for the input.

[simsjim]

How big is the filter? i.e. how many pounds of sand? I wonder if there is a correlation between the filter area and the psi - given the same size pump. I wonder because when I doubled my filter size my pressure dropped dramatically. It wasn’t a matter of dirty sand, because the season prior to the filter change, I changed the sand in the old filter. I think the water just has more area to use to get to the laterals.

There is a philosophy that lower pressures are better for filtering in a sand filter. If the gpm/pressure is too high, you may get channeling or ineffective filtering - there is a whole arsenal of water-dynamics science behind that supposition, so I'll let the more experienced folks validate or contradict that thought - i very well may be wrong, and I'd love to hear more about it. (but then we risk hijacking the thread into "The China Shop" )

Just a thought, as tenax suggests, check your max filter psi and design flow rate, just so you have an idea of your 'comfort zone'. I THINK the newer Hayward’s S series are somewhere around 50 psi max.

Those cartridge filters always sounded like a PITA to me. I love my sand.

The PI didn’t use the gauge that came with the new filter? odd....

Peace,
James

[Jeffski]

My sand filter runs at 22psi. I backwash at 30. Sounds normal to me.

[induce]

it is one of the hayward pro series S310T2. it is rated @ 50 psi.
it takes 500 lb sand. it's working great. just running @ 20 psi with pump on high. that northstar pump is moving some water.....quietly too.
does anyone show pressure when backwashing? it shows 20 then too.
the back wash pipe is only about 8 ft long and has 3 90's in it and is 1.5' pipe.
about the guage, it may be new, but it looks like the old one, they are both hayward filters, so they may be the same. it has that re-setable second hand that shows backwash time.