I was successful with the following under the floor of the brooder: 1 sheet plywood/cardboard to cover entire space taken up by the brooder(makes it easy to move the brooder around if necessary)/news paper covering the entire floor of the brooder extending outside of the walls( great for easy removal)/a covering of aspen shavings(keeps the paper dry).
When the shavings looked like they were getting dirty I doubled the shavings from 1" to 2", then the next time they looked dirty I lifted one side of the brooder and slid the newspaper and shavings out and put it all into compost pile. Next, slid new newspaper under the brooder walls keeping enough paper on outside of the wall to be able to grab it next time to remove it with the shavings also making sure the entire floor of the brooder was covered with paper and the paper extended out from under the walls of the brooder. I then added the 1" of aspen shavings and started the process over again. Sound long, but only takes a few minutes and the birds are clean and dry......
I raised the water up to where the chicks could just reach in and drink using blocks of wood; this keeps water clean. Feed was suspended up off the floor also.
This worked beautifully for 26 birds with no losses and with minimal time to take care of the birds. It is necessary to have daily water changes and food always available. Then I hardened them of and put the entire brooder setup inside my chicken tractor. Son built brooder and tractor so we could put the entire brooder in the tractor and put it outside when the time was right. That is about it.
Have fun with those little buggers. They are a lot of fun to watch.....