x,
You have a suction side cleaner, which will not work well unless you have a lot of suction from the pump.
This means the pump has to be running at almost full speed and the valve marked cleaner should be between 100% and 80% full open.
The problem is that you have two different technologies pulling you in two different directions.. VS pumps are designed to run slow to save you electrical energy, but suction side cleaners were designed about a million years ago when single speed pumps were what everyone had.
Your best option is to dump the suction side cleaner and go with a Robot that does not need the pump to run at all.. but that of course costs money..
The next best thing is to only run the cleaner a couple of times a week, when the pool needs it, and do so manually.. You would normally run your system with the cleaner port shut off and the pump running at a low RPM... When you want to run the cleaner, you would set the valve to shut off all (or most) of the skimmer and main drain, and set the pump to run at about 3,000 RPM for a few hours.
Depending on your cleaner, you "might" be able to find a spot on the valve where just ramping up your pump to 3K will make the cleaner work. If so, you can just schedule your pump to run at 3K, for a couple of hours every day..
I no longer use a suction side cleaner, the same way I no longer use the old black, rotary dial phone that my parents had when suction side cleaners were invented..

I use a robot..
Thanks,
Jim R.