My tank has some dents in it on top. What is your baking soda/vinegar mix method? I'm assuming a chemical reaction creates a gas that pops them out? How do you get the tank sealed up tight enough?irk miller said:When they build up too much pressure inside, they tend to open up like that. I've had it happen on a few tanks where I used the vinegar/baking soda mix to remove dents. You can push it back together by grabbing the seams at the bottom of the tank and squeezing together. It doesn't take much to bend it back. Just be careful not to grab the sides of the tank where you can dent it. Make sure you have a good, properly vented cap to prevent it from happening again, especially if it sits in the sun.