I moved into a new home in the Chicago area recently and, lacking a fishroom, I decided to set up a 55G tank in the basement. I just had to have some fish!

Unfortunately, the basement in my new house is really cold, typically about 65F. I like to maintain my tanks at 76F, so that would mean keeping the tank 11F above the basement temperature. I knew I should insulate the tank to lower my energy costs.

Why not rigid foam insulation?

I've insulated tanks in the past using foil-faced rigid foam insulation which is generally cheaper, but it can be a hassle for the following reasons:

  • I don't have a car big enough to get the 4' X 8' sheets home undamaged
  • It's kind of a hassle to cut neatly without denting the material
  • Since it is thick, it means you can't really use hang-on-the-back filters
  • The material has printing on it, so it doesn't look very nice unless you cover it with something or paint your tank first

A bit about insulation

The ability of a material to resist heat transfer is known as it's R-value. If you ever buy insulation for your home, it will be rated by it's R-Value. In new construction, attic insualtion is rated R-25. As a comparison, Glass is R-.91. 

Being the nerd that I am, I created a spreadsheet using some calculations from rimstart.org.  After punching in all the numbers, I calculated that to heat my 55G tank with a glass top, it would use 2.24KW per day and would require a constant 132 watts simply to maintain the termperature differential. Annual energy costs would be a bit over $57 per year!

From my spreadsheet, I then calculated the benefit of insulating the tank using Reflectix insulation, which is a flexible, foil-faced film over polyethylene bubbles (total thickness 5/16”). It's a lot like they glued aluminum foil to bubble wrap. This insulation has an R-Value of 6.91. With Reflectix in place for the sides, bottom, and back, annual energy costs were about $33 per year, for a savings of $24 per year. 

My materials cost for the insulation were about $45 and I had some leftover materials. Thus, I would have a two year payback which is pretty darn good.

What you'll need

  • One roll of Reflectix 2' X 25' insulation (Menards Link) about $25
  • One roll of 1" by 11'  Scotch Extremely Strong Mounting Tape (Home Depot Link) about $20
  • Scissors
  • Metal ruler
  • Utility Knife

 Step-by-Step Pictures

Setting Up

Lay the tank on its side on a sturdy table or workbench.


Clean the Glass

Clean the outside glass and frame with glass cleaner and a clean cloth.

Back and Sides

Start with the back of the tank. The idea is to cut a single piece of insulation to cover the three pieces of glass. Measure the total width of the back and both sides and cut a piece of insulation that is three to four inches longer.

Carefully use the utilty knife to slice through the material by running it next the frame edge. This will allow you to get the exact height needed.

Apply Mounting Tape

Unroll and stick down the mounting tape inside the frame and along the side and back edges of the tank. Do not overlap the tape.

Mark the center of the tank and insulation

The mouting tape is very sticky and once it grabs, you won't be able to realign it easily. Mark the center of the insulation and the center of the tank. You can use a piece of masking tape for this.

Remove Protective Film

Remove the top film from the mounting tape so that the top (sticky) side is exposed.

Fix Reflective Foil Insulation into place

Carefully line up the center mark on the insulation with the center mark on the tank and press over the tape to afix it to the tank.

Use some pressure,and pull the sides down and press down on the tape to secure the insulation.

Cut off Excess from Sides

Move the tank to its upright position, then run the utility knife next to the glass to trim off the excess material.

Insulating the bottom of the tank

Move the tank so that the bottom of the tank is facing up and towards you on the work surface.

Cut a piece of material to fit inside the frame edges at the bottom of the tank.

Next, apply the Mounting Tape inside the frame edges. Use either the utility knife or scissors to cut the mounting tape to length.