Having a problem! Pleco and sand bed

Hey everyone, I am having a problem. I few month back I put together
a new tank for my son with a spare 10g tank and filter I had lying
around. This is not my first fresh water tank but it is my first with
a sand bed. I have had 2 plecos come and go in it and I am wondering
if perhaps it is the sand. I know that reptiles can die from
impaction does this also happen with fish. The other fish in the tank
have been fine and shown no sign of problems. all water tests come
out fine with no ammonia or ntirates/nitrites. PH is around neutral
with my city water if I remember correctly

thanks for any info you all may have

Phatty