I don't run a check valve on mine just the drilled hole. Actually, I have two drilled, one at the water line and one just below that just in case.
I turn off my sytem at least once a day usually and so far not a problem. I was worried that a check valve woudl fail so I didn't put one in.
125g Reef Yellow,Tomini & Blue Tangs,Watchman Goby, Squareback Anthias,
60g Rimless Reef- B&W clowns,citron goby, mandarin, scooter,Barnacle blenny,firefish
125g Malawi Cichlid
90GFOWLR Red & sixline wrasses,Flame Hawk,Squirrelfish,Engineer Goby,Coral Hogfish