Cloth diapering for overnights can take some trial and error. Every baby is different, some might do just fine in a prefold with a cover, others will seem to leak even with multiple inserts. I have a pretty heavy wetter so I want to talk about what has worked for us, and different solutions that you can try if you have been having a tough time trying to figure out a good night time system.
A diaper that has worked well for us overnight is the LolliDoo Overnight Eco-Pocket. The first time I used it I did have a leak, but I emailed the owner and she was super nice and told me that most leaks happen when the leg elastic isn't adjusted to fit your baby. I re-adjusted the elastic, double stuffed the diaper and I never had any leaks again. I usually stuff this diaper with 2 microfiber inserts, sometimes I use the Flip insert, which is one of my new faves for overnights. The Flip stay dry inserts can seriously absorb some moisture and I highly recommend buying one to try if you are still looking for a heavy wetter solution.
The great thing about the Flip inserts is that you can use them with just a PUL cover during the day, but you can also use them in pockets or lay it in your favorite fitted for overnight.
Fitteds in general also work really well for us overnight. Fitteds are a good choice because the entire diaper absorbs moisture unlike a pocket or AIO where just the insert absorbs moisture. Once an insert is full there's nowhere for the pee to go but out. You can add extra layers to fitteds, just like pockets My favorite cover is wool (which can absorb 30% of it's weight in moisture, so that's even more layers!), you can also use PUL, which I do use on occasion and have never had a problem with. When choosing a fitted for night time look for diapers made with extra thirsty fabrics. Hemp and bamboo are super absorbent. I use organic cotton/bamboo on the diapers that I make (Little Owls Fitteds) and I frequently put Eli in one overnight, they work great!
Some favorite overnight fitteds of mine are Kissaluvs Marvels (I just won one of these and it's truly awesome), Little Owls (the shop should be stocked in the upcoming weeks), and the Tots Bots Bamboozle.
One of my fool proof no leak methods is putting a wool soaker or a pair of longies on my babe at night, no matter what kind of diaper he is wearing. Wool is a great idea if you are experimenting and trying to find the right system for night time use, and will result in less sheets that need washing. Want to make your bed or crib even more bulletproof? Get a wool puddle or mattress pad!