I don't have any hard PVC, it's all just regular filter hoses with hose clamps.

If I removed the sand from the filter or tried hooking the return to the pump, how many days could I do that without having an unsanitary pool? Or does that not matter seeing as my chlorine levels are 12ppm due to high CYA levels?

No matter what the outcome, I have already decided at the end of the season I'm going to remove the sand and replace the laterals. I went over those laterals 3 times each to check for cracks, breaks. Maybe something was so small I missed it. I should have just done it last season but really they looked great.