I do the same thing twice a day. I took the dry from them mid-spring to have them eat the pasture however egg production fell by 1/2. Then I put the dry food back egg production doubled.
My dry food is a mixture of whole grains and cracked corn with 10% soy meal. I ferment the same next without...
I use the expensive stuff from TSC. Go ahead and get the big sack. 25lb it'll last you a long time. For baby chicks I use the chick Grit it comes in 5 lb bags. They cost about 15 and $6 respectively. I think it's the same size as aquarium gravel. The color in aquarium gravel might not be good...