18x33 abg pool what size sand filter

[Poconos]

Sisie,
You know more about equipment than you give yourself credit for. Maybe not the details but you're tackling jobs a lot of people would just pay the pool people to do. Anyhow, the 6-way valve should be easy to eliminate. You have 3 ports. Input, Return, Waste. If you have the INPUT and RETURN (output) ports hooked up backwards then the WASTE and BACKWASH settings would not work. Flow would be blocked. WASTE is a thru path past the sand and BACKWASH feeds the INPUT to the WASTE port thru the sand backwards, that is from the bottom to top of the sand bed. In both cases the RETURN or OUTPUT port is isolated and blocked. Pressure would be very high and no flow anywhere. As for the level of the sand I comment from common sense and that says fill it as high as possible and still maintain maximum exposed surface area at the top. Fill to the point just below where the tank diameter starts reducing. Also, a little sand in the sight glass is normal. You lose a little each time you backwash so don't sweat that.
Since the flow almost stops after a few minutes of vacuuming it sounds like you're picking up a bunch of crud and plugging the filter. What kind of pressure change do you get from start of vacuuming to the point where the flow stops?
See where you stand after this and we'll go from there. This stuff isn't rocket science so I'm sure we'll solve the problem.
Al
Edit: It would help to know specifically the make/model of the filter and valve.
Edit-2: Carl did mention the possibility that the valve was assembled incorrectly. Definite possibility. Probably 6 bolts holding the thing together and there may not be any key for proper orientation of the two halves. Everything I said above will identify that problem too.

[CarlD]

OK, that's more information.
Since it SHOULD be working and, as Al said, you know more about it than you think, I'm going to toss out more random ideas to check.

Can you vacuum to "Waste"? If so, do that if you have to and add water. It sounds like there's a lot of junk in the water.

Does it backwash OK? first run water to waste for a little, like 30 seconds, then backwash. The sight glass should go clear (with a little sand) then very cloudy, then clear. It should run clear for at least 30 seconds, then put the handle to "waste" for another 30 seconds, then you are done.


Finally, was the sand marked "filter sand"? If it doesn't specifically say "filter sand" for pool filters, don't buy it. Look for the weekly sales (in my area we have 7 different pool stores I can choose from, plus Home Depot and Lowes) and when sand is on sale for $5-$6 buy 4 new 50# bags. Empty and replace your sand, and while it's out, check the laterals for clogs and damage, fixing if necessary.

As I said, I'm tossing out ideas and that's a $20-$24 way to try to fix it.

[NWMNMom]

I am guessing you know enough about your equipment to know that you have to shut the pump off in between each time you switch from FILTER to BACKWASH or RINSE, etc. Also, no air in the vacuum hose when you start to vacuum? Are you flushing the air out of that hose before you start so the pump doesn't cavitate?

[badutahboy]

I am guessing you know enough about your equipment to know that you have to shut the pump off in between each time you switch from FILTER to BACKWASH or RINSE, etc. Also, no air in the vacuum hose when you start to vacuum? Are you flushing the air out of that hose before you start so the pump doesn't cavitate?

Some very good points that most people, myself included would forget... It's been 13 years since I had a pool and did any maintenance, and I guarantee I'd have forgotten these points. Thanks for this.. It likely prevented me from posting a similar thread in 3 weeks.

[sisie5]

my sand is a hayward SP0714T SERIES VARI-FLO XL VALVE,Yes I can backwash rince with no ploblem.Here is what I did,I unhooked my new filter,and hooked up my old 100lb filter,and it does the sand thing.didnt do anything different,and last yr this work great,this is why I'm so puzzled.and frustrated.And now I have another problem,I have a leak in my liner.so Im trying to find another liner.I will keep you all posted
thank for all your help

[tenax]

are you saying that it works fine when you hook the 100 pounder filter back up or not? one suggestion if you didn't do when adding sand to a filter is to put some water in first..that way the sand floats down more gently as you add it. less risk of damaging the laterals or knocking them out of position.

[sisie5]

yes Im saying the old filter stops vacuuming to after about 3 mins,yes I did add some water first.Im ready to just give up on this pool thing