Nope, I didn't have to replace the water. At one point, I had to soak up some of the water with a paper towel because a clutch of 7 was so heavy, it started sinking, even with 2 layers of the light grating underneath. I'm thinking of using some pieces of pvc pipe to hold the grate above the perlite/water. They all hatched out fine though.

The water seemed fine though and didn't get icky.

My egg boxes didn't really get condensation on them except a bit on the sides. I had a shoebox tub filled with water in the bottom of the incubator so the humidity would equalize. Didn't make the Acu-Rite too happy, LOL. It quit working(the one inside the bator) from getting so humid.