Jon's tank build floor bracing

Second Story Reef Aquarium Build: Bracing For The Tank

by Jon Slomski

Depending on where you live or the layout of your home putting an aquarium on a concrete slab may
not always be an option. For this situation there is the weight of the tank in which we need to take into
consideration. The weight of one gallon of water is 8.35lbs. This will add up quickly in addition to the
weight of the aquarium, stand, pumps, lights, hood etc. To put this in perspective, 55 gallons of water
weighs 460lbs. , 75 gallons of water weighs 626lbs, 180 gallons weighs 1500lbs. In addition to water
weight we need to add everything else associated with the setup.

Know Your Load

Now we need to take into consideration that a residential second floor or a floor with a basement
underneath is only rated for a live load of 40lbs per sq/ft. A live load is anything above and beyond
building materials and the construction of that house. A typical residential floor can mostly likely hold
quite a bit more than what its rated for but we have to keep in mind all the variables… age, wood type,
size of joist, direction of joist in relationship to tank and if the tank is up against an outside or load
bearing wall.  Also keeping in mind that you want to stay WAY under the breaking point!

So let’s to do the math… a 55 gallon fish tank and full set up would weigh roughly 750lbs all together and have a  foot print of roughly 4 square feet. This would be a weight of 187.5lbs per sq/ft. A 180 gallon fish tank and full set up can weigh up to 2000-2500lbs. This would equal 250 – 315lbs per sq/ft. This is 5 times what a residential floor is rated for.  Chances are the tank will not come crashing through the floor but the biggest concern would be the bowing and sinking of the floor under that weight for an extended period of time.  So what do we do? The floor needs to be reinforced or braced to withstand the weight of the tank system.

Jon's Tank Build Floor Bracing

There are several ways to do this. I my case I need to account for a 180 gallon tank plus a 55 gallon sump plus a 20 gallon reservoir plus a stand, hood, lights, and hardware. My tank was going to be on an outside load bearing wall so the back side of the tank was not what I was worried about. My joists were running long ways with the tank so my main concern was the first joist that was going to be holding the weight of the front half of the tank.  Without additional support this would have most likely bowed up to 2 inched in just a few weeks.

Bracing The Floor

After much research I decided the best course of action would to put 3 support beams from the basement floor to the bottom of the plywood of the floor the tank would be sitting on. I centered this as well as my homes construction would allow to sit direct under the front wall of the tank and stand.  First was to fasten an 8 foot 2×6 to the plywood. This would allow me a little distance on each side to situate my tank upstairs. I then used a 2×4 on the bottom side of the 2×6 to brace the support beams I was going to use. You could use a 4×4 for extra piece of mind if you decide. As for the support beams I doubled up 2x4s from the concrete floor to the 2×4 under the 2×6 now attached to the ceiling of the basement.

I used “C” brackets both on the top and bottom of each beam.  For the top brackets I drilled them right into the 2×4 on the ceiling.  For the bottom “C” brackets, I actually mounted these directly into the concrete floor.  You can buy concrete screws with a drill bit include in the box for this project.  An electric drill and a little elbow grease took about 30 minutes to drill 12 holes total ( 4 holes per bracket ).  Next, we placed beams in each bracket and made sure they were level to get the correct placement on the bottom brackets before securing them to the concrete.  I then traced the bottom brackets for placement once everything was leveled. After each top and bottom bracket was secured we placed our support beams ( 2 2x4s or a 4×4 ) in and secured them with decking screws.  This bracing, if done correct, should eliminate any bowing or sagging issues under the weight of the tank.

Stay tuned for more updates on the tank stand build and plumbing shortly!