I finally found a good system for my newts that was mostly things i had around the house.
Use an in-tank filter than outputs water in a tube fitting, get about 5 feet of that tubing (sometimes comes with the larger models in the box), I used a gravel vacuum that happened to fit. Run the tube through the lid into a cooler filled with water and frozen water bottles, ice packs etc and back into the tank. The tank water should never touch the cooler water. Keep an eye on temp and change the ice packs as needed. It was 90 deg today in the house and I had to change it twice, but when my house is in the 70s I only change it every other day. I easily get the tank from 84 to 65 in an hour and it maintains for many more hours.