It's now Oct, and it will be getting cold and rainy before too long . . . which is exactly perfect from my perspective. Yes, cooling and ventilation does matter, a lot. Trying to grow anything indoors during the peak of summer heat is not going to do very well unless you have serious AC and ventilation going on.

Even though I'm a novice when it comes to hydro growing, various friends have been at this for awhile, so I get to have a bit of first hand advice and observation. In my situation, I'm just growing a few plants, so I don't have the seriously intense lighting and temp control requirements that others may be dealing with. Depending on the type of lighting used, there is going to be a lot of heat. I've been looking into LED lighting, as it runs much cooler than halide, for instance, but it's also quite pricey to get the same amount of lumens that halide lighting can provide.

Good luck . . .