I know about probiotics and have been using Gro2Max. My chicks are 4 weeks and I use the nipple water system and a bowl. Even though I filter the probiotic I get just enough grit that the water nipples do not work properly. I would like to use a liquid probiotic instead of powder. I can not find on their site where it specifies the age. Can anyone help me? I am open to another brand that does well, also.