Hi, I've recently changed sand in my filter guided by a video I found on Youtube. It said to fill tank with water prior to adding the new sand to prevent damaging the laterals which i did. Unfortunately after all is said & done, ive got sand coming out the backwash water as well as in the pool & now im prepping to take it all back apart & scoop out all the sand to inspect the laterals more closely. I'll probly just replace them regardless cuz i may as well. But i was wondering if anybody can tell me whether or not the water all by itself, no sand, should remain in the tank or if it should be draining slowly as i work? Also I've just got the basic push pull valve which is filter/back wash. Anyway i did the job right. Thoroughly cleaned the tank and the seal area along with the clamp etc, used the right sand & amount. I've been told the most common cause of sand in the pool is broken laterals however ive also been told that it could be the water rising too high during back wash. Also that after a sand change it is not uncommon. Thanks I would appreciate any feedback on the matter cuz if ots suppose to be holding water & isn't, i may need to be looking at the O rings further down beyond the laterals yeah?