I've run the intake of my pump from the outside, probably does keep the water a bit cooler (it's been warming up a bit in the daytime so it's kinda hard to tell until it gets frigid) since it seems to cool the metal manifold that used to get pretty warm pulling room air.
I thought of that, but didnt want to put them right into the res because i dont want my roots to be touching them. I think it would be a shock for them. I dont have a tub big enough to put my res in so that i could put the bottles in there
Take a look at your setup, if your air pump is by your lights, or under the lights then it's going to be warmer then not. Moving my air pump up by my AC, and away from my lights helped to drop my temps a bit, but ice bottles work best!
i have only ever grown in aero and dwc and i used frozen water bottles for years and still do in my 5gal buckets. these are weeds, man, dont get to caught up in all these little things about stressing this and that or add this or dont do that. keep it simple. the roots will be fine. hell, in winter my tap water is below 40 and i add it straight in.