So I inspected the valve and seems to be fine, how can I check the spider gasket and key valve?
You would have to remove the top and inspect it. As for the blue handled ball valve on the pressure return line, the handle might turn fine but inside it could be bad. Something to think about if you exhaust all other options.
So I took off that valve and everything seems fine, is it possible that my sand filter just works at 20psi??
Every pool is different, but yes, the psi on your pool could be completely different than your neighbor. Keep in mind that algae and the previous use of clarifier will make the psi read much higher as well. So if everything mechanically seems fine at the pad, you might find it best at some point to just replace the sand and then resume the SLAM Process.
But if the clarifier was ever allowed to reach the sand, the consistency of the sand is compromised. Same thing with floc. That's why we almost never recommend using those products here at TFP. When you think about all the troubleshooting we've done on your system, there are only a couple things remaining - the pressure side ball valve or the sand. That is of course assuming the MPV is operating correctly.
But the sand wouldn't be a problem in recirculation mode, right?
Correct. It shouldn't be unless there is something wrong with the MPV allowing water into the filter when it shouldn't.
That blue handled valve just past the SWG.
If someone changed their jet sizes to smaller, sure, it could result in more back-pressure. But I don't think that applied to your scenario.
I'm going to preform the deep clean now, should I use a bit of filter cleaner?
So I finished deep clean and nothing changed. Going to order new mpv and see what happens.
What he was saying is the orientation of the cell is backward. Flow is supposed to enter the end with the cord, and exit the other end. Based on the design of the cell, I don’t see why that would impede flow, but to be properly installed, it should be turned around. As for pressure, if the MPV is good and the filter is clean, I don’t know other than the small size of the piping. But it worked fine before, right?
