What if the humidity is wrong in my incubator?

I'm now incubating chicken eggs. They say it takes 21 days for them to hatch. So far, I think everything is doing good. I candled them tonight day 18 and it is a brown egg so its hard to see it good. All I seem was a big black mass with an air pocket at the top or bottom of each egg. My grandfather and I also took the automatic turner out today. We are using a little giant incubator. I know you have to raise the humdity to like 70% but I don't have a hygrometer to measure it. So, I refilled the styrofoam rings in the bottom like my grandfather has been doing and then also put in half of styrofoam cup full of water. Will they still hatch? Will my eggs be okay? Have I done anything wrong?

It sounds as if you and your grandad are doing just fine. The hardest thing now is to leave the incubator in lockdown, ie do not be tempted to open it whilst the chicks are hatching because this will instantly lower the temperature and humidity and be a shock to the chicks. Leave them in there for 24 hours after hatch to dry out properly and have th brooder all warmed up before moving them. They don't need food or water whilst drying out as they are still absorbing the egg sac. Good luck for a wonderful hatch!