Dagmar, You could also wrap the containers with an insulating material, like bubble wrap or foam packing, I wrap my reservoirs with the large bubble , bubble wrap and it helps keep the temperature down (or at least, in my mind ! lol). Also, if the containers are black or dark colored, and exposed to the light then wrap some aluminum foil around them to reflect it back. Remember it's only crazy if You wear it on Your head !! LOL.