Latewood; You wrap the sides and bottom with that stuff, the idea is to keep the water at an even temperature from the top of the water to the bottom of the water res. Harbor freight tools have the PVC welders on sale for 25 bucks. Most others are selling the same tool for as much as 500 bucks so the 25 is a good deal. Take them up on their offer for the extended warranty too. Just remember to start the airflow before you plug it in. Don't stop the airflow until well after you turn off the heat so it cools down.