Let's call
@Mdragger88 and
@zea3 and see what they think...
Putting a third valve #2 between pump and filter would isolate the pump, allowing you to clear the basket. However, if the MPV has a "closed" position, this would be the same. If the new filter has a closed position, then you would only need the closed position on the MPV and on the skimmer (one diverter). That would isolate the pump.
The biggest risk to all of this is starting the pump the diverters/MPVs closed, dead heading the pump.
Okay, I think we are finally on the same page. Sorry, 12am posting might have contributed to potential confusion.
Of course to clean the pump basket, I need to stop flow from both sides, i.e. from skimmer to pump (valve #1) and from return to the pump basket on the other side of the pump. For this I was going to use to use the "closed" position of the MPV, effectively stopping flow from return side.
I'm trying to get away with only necessary valves. To clean the basket, I do need valve #1 so I don't have to climb on the deck to put the stopper in the skimmer. And the close it from the other side via MPV.
If I do need to do bigger maintenance to the filter, then I don't mind climbing up and plugging the return with a stopper.
I think to keep it simple, valve #1 very necessary from convenience standpoint. Valve #2 likely overkill. Valve #3 would be nice, but also can be substituted with stopped. And of course being very careful not starting pump with valves closed/stoppers in place.
Unless the others suggest throwing valves #2 and #3 in anyway, I won't.