# Another Aquarium Rack



## jcabage (May 29, 2012)

Just curious to see if anyone finds any structural or stability issues with using this setup. It's just the standard Dado-joint design, but my biggest concern are the board choices vs. aquarium weight, etc.

I plan to use 2x6's for the side posts and the framing for the middle tank (75). I'm thinking I can use 2x4's for the framing for the bottom tank (75) and the top tank (either a 40 long or 33 long, haven't decided).

I'm not an engineer by any stretch, but it seems that a couple 2x6's could hold the weight of that middle 75 with a dado joint, the 2x4's should be able to manage the 40/33 on top, and the bottom 75 will just be sitting on 2x4's on the ground.

Any thoughts would be appreciated!


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## atreis (Jan 15, 2013)

Span tables (use No. 2 Southern Pine - that's what's commonly available at Lowe's/Home Depot)

Assuming your span is 4' and the tank depth if 18", you have a footprint of 6 square feet. The 40L on top will be ~400 lbs, or 66 psf, 33 psf per beam, and should be considered live load. (Use the joist spans in the table.) They don't list 2x4 (no one uses them for joists!) but scaling down from 2x6, you get something like 6' span being okay for 40 psf, so the top tank is good.

Figure the 75 in the middle at about 750 lbs, or 62 psf. Span table says 2x6 is good for 9' at 40 psf. It's kind of hand-waving, but less than half of that span at half-again the psf should be no problem at all.

Presumably the bottom one is sitting on the floor.

BTW - not sure where you're putting this in your house, but you've a total of almost 200 gallons on a 6 square foot footprint, which is quite a lot. If you're not putting it on a cement floor, you'll almost certainly need to reinforce your floor joists under the whole setup. (You'd only have 3 joists supporting close to a ton if it's running perpendicular.) To do that, you would want to call in a structural engineer.


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## spotmonster (Nov 23, 2006)

Bottom line, 2x4's is all you need for the entire thing :thumb:

As for the design, it's fine, no issues and commonly used.


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## jcabage (May 29, 2012)

These are just the things I wanted to hear. I figured as much, but I'm not one to know when a board will break. There are no concerns of sideways motion either? The stand itself is 72" tall with the 33/40 on top of that.



atreis said:


> BTW - not sure where you're putting this in your house, but you've a total of almost 200 gallons on a 6 square foot footprint, which is quite a lot. If you're not putting it on a cement floor, you'll almost certainly need to reinforce your floor joists under the whole setup. (You'd only have 3 joists supporting close to a ton if it's running perpendicular.) To do that, you would want to call in a structural engineer.


We do in fact have a cement floor. That was one of the major perks of the home we are purchasing


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## Deeda (Oct 12, 2012)

I also agree that using 2 x 4's for the main structure is sufficient. Where I think you will have some problems is with the addition of the tank at the top. A standard 75G tank is roughly 22" tall and I would leave at least 10" between the top of the tank rim and the bottom of the beam for the shelf above it, preferably more for better access. Water changes and maintenance on the bottom 75G will also be a bit more difficult, especially if you use gravity to drain the tank.


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## spotmonster (Nov 23, 2006)

There are no concerns of sideways motion either? ...

No, but you can add bracing to anchor it to a wall if you have the option, It won't hurt.


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## jcabage (May 29, 2012)

Deeda said:


> I also agree that using 2 x 4's for the main structure is sufficient.


I'm glad to hear this so confidently. I think I'm going to stick with the 2x6's, but the extra assurance is really appreciated.



Deeda said:


> I would leave at least 10" between the top of the tank rim and the bottom of the beam for the shelf above it, preferably more for better access. Water changes and maintenance on the bottom 75G will also be a bit more difficult, especially if you use gravity to drain the tank.


We have approached both of these things in the past, and I think I'm going to brave them again. I'm planning on 8" of space for the bottom tank and 7.5" of space for the middle tank access. We've got a 40 Breeder rack that is similar now with a tank on the floor and ~8" of wiggle room. While inconvenient on some days, the good seems to outweigh the bad.

I do appreciate the advice though. getting that bottom tank started siphoning is almost always a pain. :roll:


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