Possible solution for you..here in Salt Lake we’ve had awful heat, like 105-106, and my girls are 17 weeks this week, so, their undersized mass helped with the heat, but, I used the Santa Cruz electrolyte powder, but in their (organic Modesto) food. I put a scoop on top, misted with water so it didn’t all just fall off and go to the bottom, mix it, along with some organic herbs. That way the electrolytes are in the food and they can drink as much water as they need to flush the salts out. I also read in Gail Damerow’s book Chicken Health about not using ACV in extreme heat as it messes with calcium metabolism. So far, my girls have done great with the heat and my solution. They can get under their coop, and I’ve covered the run with shade cloth as the heat and sun are brutal. In the water I put probiotics and a vitamin preparation, the Durvet product with Vit ADEK I believe.. I would put ice cubes in their water in late afternoon, read that they prefer 55ndegree water and will not drink hot water. I keep their water under the coop in the shade, wash it every day with soap and water when I bring their food and water inside my house at night to prevent any possible rodent attraction or contamination..
edit..I bought a portable swamp cooler for the coop to cool it during the day with the extreme heat..I have to turn it off at roosting time, they don’t like the powerful fan!
edit again! I also would spray water under the coop at night so the next day the breeze helps make cool spots, and occasionally during the day for them to walk around on it to cool off..that and cold watermelon, frozen corn niblets in muffin trays, etc..
I think it’s important to keep electrolytes out of the water for healthy chickens so you have that safety valve of being able to drink fresh, pure water to flush any excess electrolytes out of their systems. It’s different for sick or already heat stroked-out birds, it might need to be in the water at that point..