I had two Aquaclear 70's running on my 55 gallon for a long time, and they were running way before that. I switched the 55 up to a canister but I still have one 70 running on the 55 and I moved the other to a 36 gallon. Both are and have always ran great.
My 55 is sand substrate and I have never had a problem with the sand getting in the filter, of course you don't want to go in there and just mix the sand all up. They are IMO
one of the best, if not the best HOB
for the money. You have a lot of choices as far as media with a dual setup.