I'm not sure this is your issue, but I had something similar to this. I had bought 2 BYM pullets (one ended up a roo actually) and they all had so much cecal/runny poo! This was around 3/4ths of their poo being cecal. Well, I realized on top of me giving small bits of bread (half a hot dog bun to 6 chickens every 3 days) my family was giving them too and encouraging that as an extra snack some interested kids on our block could give to them too. We did do the hot pepper natural dewormer since we weren't sure what was causing it but wanted to rule out worms. Didn't fix the issue at all. Removed the bread and it was significantly better in a few days and in a week they were pooping a normal 1 cecal to 7 normal poos. The bread only affected the BYMs, but it was still significant. So, the question is, what is their food?
Also, a cecal float is a great idea no matter what. It's also a good idea to squish down and inspect suspicious poos to check up on your chickens' health.