Adding Unions to Sand Filter and Filter Maintenance


Well-known member
Apr 2, 2012
Florida Panhandle
Greetings TFPer’s, hope everyone is doing great this summer day and everyone's pool is crystal clear and balanced.

It’s amazing what a new liner will do in terms of wanting to make everything else new and I once again need everyone’s expertise on a few things and I truly appreciate the help.

I recently had a new liner installed (old one was faded and 11 years old) and to be honest I kinda let my pool go in terms of chemistry during the past year, only adding LC every 2 to 3 days and sometimes acid, the pool wasn’t green but it did have algae near the end, so I want to make sure that the inside of my sand filter doesn’t have any scale or other surprises. The liner installers did backwash before starting up the filter after the install, by my request thank God, and they said they were glad I told them too as it was really nasty. My pool is currently clear as can be (knock on wood), both from the outside and looking inside using a mask, the only thing I’ve noticed is when the LED light is on at night, you’ll see the occasional small things float by, but not sure a sand filter can even get those small things out.

My Hayward sand filter S244T is about 7 years old, installed 2012. I changed the sand to the Zeosand last year, April 2018, (yeah I drank the Koolaid) and been running the pump about 19 hours a day (mainly on 1000 RPM's with a few hours at 2800) since I had it installed as I got a Variable Speed pump the same time. Anyway, that’s the history with the equipment. I haven’t replaced anything, the valve or laterals and if I remember correct, the tech that did the sand to Zeosand swap said my laterals looked great. I think he of course replaced gaskets but not sure, but I know the valve hasn't been replaced, I've only ever sprayed some Silicone spray lubricant in there to help out and not sure that was ok but it worked.

So this leads me to today’s questions….I want to install unions so that I can easily remove the valve and perform deep cleans when I want as well as if I ever have to top off my sand or check\replace o-rings\gaskets and with the current setup, pics are below, I would have to cut the pipe every time.

I am not sure the size of my pipes, I believe they are 1.5 inches and when but when I measured around the outside of the pipe, I get about 7.5 inches and when I Googled that circumference of a PVC pipe, 2 inch showed up?? So far everything I’ve read here and everywhere else says it’s a 1.5 inch pipe. Would anyone be able to help determine this with the pics I’ve attached or is there another way to measure the connected pipes?

Assuming they are 1.5 inches, would I then just be able to order 3 of these types of unions ( 2 PACK -CMP Hi-Temp Union 2" inch 2MIP x 2" inch PVC Whisperflo & Intelliflo - 2 PACK: Garden & Outdoor) and then just install them where the red marks are on the pic below? I recently just got a SWG installed and they moved the Polaris piping up on the return line and installed new piping.


When cutting the PVC pipe, is there a specific amount to cut out or do these unions have instructions that indicate this?

I’ve primed and glued PVC pipes before as I added Waste line so that it would come out into the driveway so I could direct it to the street but I’ve never installed unions before, so hoping it isn’t too difficult.

With the unions I linked above, I assume since I have a Salt Water pool, that I would just need to check the O-rings maybe once per season and replace when necessary?

Lastly, while I am doing all this, I might as well replace the valve as it has never been replaced and I’ve attached pics below so you can see the condition. I am still able to turn it but it looks like there is rust in there. Should I also go ahead and replace the entire lateral assembly too, that way I would really have a brand new filter with the exception of the year old Zeosand:




I am still reading all the existing sand filter maintenance threads and union related posts to help but figured it might just be easier to go ahead and post my situation.

Thanks for any and all help and guidance and hope everyone has a wonderful and safe weekend.


Well-known member
Apr 2, 2012
Florida Panhandle
Might be overkill but now thinking of just buying this ( Hayward SP0714T VariFlo Top-Mount Control Value, Black: Garden & Outdoor) since I assume it would come with everything (new spider gasket and o-ring) and then just order 3 of those unions I linked above (if they are recommended) since I’m thinking they would just screw into this replacement multi-port valve assembly. Not sure if I would just be able to screw them in or if so would need to use Teflon tape? Still not sure though as those unions are 2 inch?

Would probably wait on the laterals as I don’t feel like taking all the sand out unless so come across something when inspecting the Zeosand.

Not sure if I would need anything else, special o-rings due to the salt, etc.

OR, is it worth it to just disassemble everything and clean and put any rusted parts in CLR? Just didn’t know if it was worth it and if it would compromise the integrity?

Thanks again for any help and advice.
Last edited:


Well-known member
Apr 2, 2012
Florida Panhandle
Apologies for all the posts, but as you can tell, I’m continuously reading as much as I can.

If the Sand Filter uses 1.5 inch piping, then I saw the below 2 union options from other posts:

Thanks again.


New member
Jul 6, 2019
If you can remove any of those fittings from the valve and other hardware Hayward has a union that screws right in. I just used a bunch of those to hard plumb everything with a mix of pipe and flex pvc. Might be easier to just replumb with the flex pvc if you have to start ripping stuff out already.
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