Well first off recharge I use it awsome stuff.. hydroguard has some bennies in It as well but I prefer recgarge. As for the temps ideal is 65-68. The reason for the temp is keep root rot at bay. And better do levels. Personally I would recommend res change on Fri mix up recharge sepreitly in a little pitcher or cup about 12-to 24 Oz water. 1/4 tsp recharge mix really well and pour it directly at the plant stock. It will drip from top to bottom getting all the Bennie goodness on them. I could spend a hr talking about the awsome shit in rechage. Dudegrows out of Colorado knows there shit. During the week I would top off with plain ro/ph'd water. And add recharge at least 1 time a week I like to do it every time I add to me res. I used to use a chiller on my rdwc system but noticed it wasn't needed after I kept my root zone inoculated with beneficial microbiology.