Good morning! I currently have sand returning to my pool through return lines. 2019 I replaced sand in filter. May of 2020 emptied sand and inspected laterals and bought new laterals due to some cracks and corrosion. Refilled with sand and subsequently had sand return to pool. May of this year I emptied sand filter again to make sure all lateral arms were pushed down and that no damage was present. Took lateral to local pool store where I bought it (good people) for them to eyeball. No damage found. Put it back and bought new sand to be sure the size of sand was correct. Running the pool and sand is present again on the bottom of return side of pool. Ugh! My pool is 5 years new to me (former owners did not care for it well). So here is the big question, any chance the sand is getting pulled into the pool because of the multiport valve? Thats the only thing I can figure out at this point. When I put the laterals back I did so very carefully and added water before gently scooping 200lbs of sand in so I know its nothing that happened when I put it back together. I appreciate any feedback. Thanks!!!