How to suppress/disable an SLVS?

[berniedp]

Hi all,

after (too) many SLAMs over the past 1.5 years I think I have established that the SLVS that's installed on my pool is the culprit...
(previous post on the topic, just as background: Pipe in my yard - no idea what it's for)

As I'm again going through a SLAM, I've looked again at this SLVS and I have established that the water in that pipe is most definitely stagnant - I took some of it from the open pipe (about 24 inches down) and tested it for chlorine (FAS-DPD): there was absolutely none in it. The water was dirty as well, like soil got into it...

So, I switched off the pump, opened the filter (cartridge), drained all the water and put everything back together. I then watched the content of that pipe while I remotely (from the app on my phone) switched the pump back on and saw that while the pump was priming it basically sucked out all the water from the pipe. Once it was primed and started running at normal speed, the water returned to the pipe. I repeated this exact thing a few times more, this time also closing the valves of the robot and the skimmer and could see the dirty water ending up in my pump.

So I believe that every time the pump has to prime or a vacuum-like event happens (like I had recently when the hose for the suction vacuum robot was disconnected and that suction port closed quite abruptly) it's pulling in that and may very well be causing the cloudy-ness of my pool once it gets mixed back in with the main pool water... It's not impossible that my variable speed pump is much more powerful than the pump that was originally there and the change in the valve layout (the original pool didn't have a suction valve for the robot), is making this SLVS inadequate.

So, to my question: as I have 2 main drains, I don't see the need for this SLVS (they don't put them in new pools anymore in FL) so I want to suppress / disable this thing all together. Now, as I'm not an expert, I was hoping if anybody here could give me a pointer as to how to do this? I mean, I know I'll need to cement a PVC cap on the pipe but is there anything else I need to think of? Can I do it just below ground level or should I try to go deeper (though it may cause the pipe to overflow if I go below the pool water level)?

Thanks,
B.

 

[newdude]

Are you capable of blowing it before capping? I would blow it, dump a couple bottles of bleach in the pipe, then cap it just below grade. I'd drain some pool water if needed so it didn't flood.

 

[berniedp]

Are you capable of blowing it before capping? I would blow it, dump a couple bottles of bleach in the pipe, then cap it just below grade. I'd drain some pool water if needed so it didn't flood.

Hi @Newdude - I was thinking of going the inverse by pumping out some water which I guess would achieve the same?
Otherwise I'll talk to the pool guys to see if they can do it - perhaps they have a way to blow it out...
Good suggestion though!

 

[newdude]

I was thinking of going the inverse by pumping out some water which I guess would achieve the same?

So long as it's emptied / replaced with fresh pool water before its capped.

From that point on it will never suck the whole pipes worth of yucky water at once. Maybe a tiny bit will escape into the suction flow from time to time, but that will be easily handled by 6k+ gallons of properly treated water.

Without that cap (aka 'finger on the straw'), the whole pipe is emptying everytime the pump cycles back on.

 

[JoyfulNoise]

Dig down and redo them plumbing. That’s the only permanent fix.

 

[JamesW]

Because it is considered to be a safety system, we cannot recommend disabling it.

I recommend that you get a qualified professional to advise you on what options you have for removing the system in a way that is safe.

 

[berniedp]

Side note: I wrote the above article while going through a SLAM, which ended on April 30th, after 17 days...
On May 7th I had the pool guys come out to 1° replace the non-code main drain covers to code, 2° check why I was seeing air being sucked into the pump when my robot was disconnected and 3° discuss suppressing the SLVS.
Item 1° was a no-brainer, 2° was apparently caused by a faulty O-ring in a valve - so nothing major neither.
On item 3, however, the guy was adamant that an SLVS may not be suppressed if it's already installed, even if I have 2 main drains in the deep end (which is FL code requirement I saw).
Since finishing my above mentioned SLAM, my FC never dropped below 6 - measured daily, with a CYA of 60. I try to keep it around 8.5 and up/down my SWG depending on the FC need.
On Saturday, with everything being stable, I added CYA to take it from 60 to 80 (as 75 is kind of the middle ground between the suggested 60-90). I also added a cup of chlorine to the SLVS pipe (thinking I can't hurt).

And again, on Sunday, my pool water started becoming opaque - yesterday (Monday) it was at 6.2 in the early AM - as I didn't have liquid chlorine on hand I pushed my SWG to add more and then did a OCLT and I lost almost 2ppm... So I started a SLAM today (unfortunately I increased my CYA so my target is high...)
I don't really understand how this is happening - if I stayed in the good FC range, then why is it opaque again?

I still believe the SLVS is the culprit as I can't think of any other causes... With the O-ring being replaced, perhaps the suction towards the main drain increased (can't imagine it being such a big difference though)

This is what the valves look like:



I have the bottom valve set to reduce the suction from the main drain to the max but don't want to close it completely as the water would probably also become stagnant. Or is this exactly the issue? Is it closed too much?

Does anybody have any other ideas? Suggestions?

Here's my pool on poolmath: PoolMath Logs

Thanks a ton in advance,
B.