I'm also looking at running bubbleponics on my next run and have been doing a fair bit of research. Some quick points for you.
- Be mindful that the submerged pumps will also raise the water temps.
- The lower the temperature, the more dissolved oxygen the water can contain.
- The higher the water temp, the more oxygen the roots will need but the water contains less.
- Higher water temps (75-85) is ripe breeding ground for cyanobacteria (aka slime algae)
I'm going straight to a chiller and not messing around with the temps but some people freeze 2L bottles of water and put that in their reservoir but imo thats a lot of work all the time and unstable. They have them for reef tank setups so check prices from aquarium supply places. The Hydro section of this forum has a wealth of info stickied