hatch rate can have a lot to do with many different factors. i too own a 1588 with an egg turner. and i have always used a carton, except for my 1st couple hatches. i love it cuz it keeps the eggs stable when chicks are having a party in the bator. i usually cut the bottoms out of my cartons so the carton looks like 12 rings....i do this cuz i read somewhere on here about air circulation etc. i candle before i put them into lockdown and i use a pencil to trace around the air cell (not perfectly) but just to get an idea which way it's slanting (it's very rarely perfectly on top) and then i slant the egg so that the air cell is facing more up. anyway, all my eggs are slanted away from the incubator wall too (if the carton is smack dab up against the wall) cuz i don't want them to have any problems popping their top off. u'll find load of info here on the subject. some people sware by it, others would never do it. i personally like it, it's a personal decision.