Question on pressure

[cmdr-s]

Is there a "normal" pressure for a sand filter?
I've been SLAMing for a week, with no improvement to green water. Visibility is approx 3.5 feet.
After backwashing, my pressure is 10-12 psi and flow out the returns seems good. If I take in water only from one skimmer and a vacuum port located half way up a wall, the pressure never increases, as if the filter is not doing any cleaning . If I vacuum the bottom, the pressure increases in just a couple minutes, and flow out the returns all but stops. When I backwash for 2 min, followed by 30 sec rinse, a stream of "dirt" comes out the return lines for about a min.
I've vacuumed the bottom to waste best I can (without being able to see the bottom). I've checked in the past for channeling, but don't see any obvious signs of that.
Beginning to wonder if the pump isn't putting out enough pressure to properly circulate water through the system.

 

[Texas Splash]

Is there a "normal" pressure for a sand filter?

Yes and no. Ha. It's easy to speculate that some pressures might appear to be acceptable, but then each pool is different based on plumbing and equipment. Throw in water chemistry and it all goes out the window.

So let's start there- chemistry. Can you post a full set of water test results?

 

[cmdr-s]

Yes and no. Ha. It's easy to speculate that some pressures might appear to be acceptable, but then each pool is different based on plumbing and equipment. Throw in water chemistry and it all goes out the window.

So let's start there- chemistry. Can you post a full set of water test results?

PH lowered to 7.2 prior to SLAMing, per instructions. Haven't checked since.
Alk 200
CYA 25 (added 7.5 lbs of stabilizer this week)
Been keeping the Chlorine at 10
CC is 0.5 (I have NEVER seen a CC reading over 1.0)
OCLT is 1.0 or less
Had a full day of bright sunshine today. Chlorine dropped from 9.0 in am to 6.0 at sunset. Shouldn't sunlight have burned off more chlorine?
Added some DE to increase pressure 1-2 psi. Over several hours, pressure will increase to 20 or so. Flow lessens.
BTW: I have a Hayward pump/ 1HP motor. Hayward filter with multiport connected to side of filter.

 

[HermanTX]

CYA 25 (added 7.5 lbs of stabilizer this week)
Been keeping the Chlorine at 10

We would call this a CYA of 30 - always round up to the next decade number. Therefore your target FC level should be 12ppm during the SLAM

Chlorine dropped from 9.0 in am to 6.0 at sunset. Shouldn't sunlight have burned off more chlorine?

You should test every 4 hrs during daylight hours and add more liquid chlorine to get back up to SLAM. Having a FC of 6 is not helping. The more you hold the FC at 12ppm the better the SLAM will go.

Vacuum to waste is good - even if you cannot see the bottom. However, you should test afterwards because you have drained some water. Also brush so you can stir up the algae to filter it out.

 

[PoolStored]

PH lowered to 7.2 prior to SLAMing, per instructions. Haven't checked since.

Great, don't worry about pH at this point.

Alk 200

Ignore for now

CYA 25 (added 7.5 lbs of stabilizer this week)

Is this CYA reading now, after you dissolved CYA and waited 24 hours?

Been keeping the Chlorine at 10

You CYA is 30. We only read CYA at the lines, or round up. You should target FC at 12! 40% of 30 = 12 FC for SLAM

CC is 0.5 (I have NEVER seen a CC reading over 1.0)

Great!

OCLT is 1.0 or less

Great! That means it is a filtering game at this point. Can you post some pictures of your current water?

Had a full day of bright sunshine today. Chlorine dropped from 9.0 in am to 6.0 at sunset. Shouldn't sunlight have burned off more chlorine?

Eh, maybe, maybe not. We are early in the season. At peak JUNE, northern ohio, with sun and swimmers I use 5.5 FC.

Added some DE to increase pressure 1-2 psi. Over several hours, pressure will increase to 20 or so. Flow lessens.

So here is the deal on filtering. Sand will be the slowest filter to clear slam. Backwash, rinse, note clean pressure. When pressure rises 25% over clean pressure backwash, rinse, repeat. Now is the long game to clear the dead stuff.

BTW: I have a Hayward pump/ 1HP motor. Hayward filter with multiport connected to side of filter.

Great!

 

[cmdr-s]

Great, don't worry about pH at this point.

Ignore for now

Is this CYA reading now, after you dissolved CYA and waited 24 hours?

You CYA is 30. We only read CYA at the lines, or round up. You should target FC at 12! 40% of 30 = 12 FC for SLAM

Great!

Great! That means it is a filtering game at this point. Can you post some pictures of your current water?

Eh, maybe, maybe not. We are early in the season. At peak JUNE, northern ohio, with sun and swimmers I use 5.5 FC.

So here is the deal on filtering. Sand will be the slowest filter to clear slam. Backwash, rinse, note clean pressure. When pressure rises 25% over clean pressure backwash, rinse, repeat. Now is the long game to clear the dead stuff.

Great!

thanks for the responses, folks. I'll bump the FC up to 12...and wait. Anxious because we have guests visiting next week. Too cold to swim, but would be nice to have somewhat clear water. I didn't open the pool at all last summer and that could be adding to gunk levels.

 

[mknauss]

Painted pool. Do realize pool paint does deteriorate and can cause cloudy water.

 

[cmdr-s]

Painted pool. Do realize pool paint does deteriorate and can cause cloudy water.

Yeah, paint is flaking in some areas. Prepping and repainting isn't something I ever want to do again.