# Is my Tank Rack Strong Enough?



## bntbrl (Apr 23, 2009)

I built this entire rack around 100 usd. Give or take 5 or 10 dollars. Tanks and all. The wood is 2x4s, and the cross braces are 2x3s. Every joint has 5 wood screws except for the load bearing joints that have 2 Spax lag screws rated at 265 pound shear weight, and 2 or 3 wood screws or more.

The bottom tank is a 45, the left middle a 30, and the right two are 20 gallons. The ones on the top are 2 10 gallon and one 20. Its in the "dungeon" room and although I was going to go with something nice looking I opted for cheap as teh room looks like a torture chamber and no one goes in there anyway but me. Theres a drain on the floor so it made sense to put my "fishroom" there. This is the first part. Ill likely build two more that go around the wall in that end so theres at least 15 feet and another rack like this one as far as room goes. Some boards were already cut so that I had to build it this way. It seems very solid. However the 20 gallon is pushing 160 pounds and the 30 gallon is pushing 240. The bottom tanks should be fine and I feel the upright 2x4s would hold up a VW beetle. The 30 and the middle 20 gallon are what Im mostly concerned with.

Any thoughts or ideas? I beleive that it is strong enough. However theres people wth more experience than myself.


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## mightyevil (Oct 23, 2008)

I would put a piece of plywood on the backside and make holes accordingly for your cables, that will help it considerably. Other than that I think it will hold well.


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## bntbrl (Apr 23, 2009)

I never had acrylic tanks before. Someone brought it to my attention that acrylic needs a full support on the bottom of the tank. These two only have cross supports near the edges.


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## mightyevil (Oct 23, 2008)

bntbrl said:


> I never had acrylic tanks before. Someone brought it to my attention that acrylic needs a full support on the bottom of the tank. These two only have cross supports near the edges.


It looked like you had support in the bottom from the angle of the picture. You will need full support under those tanks, acrylic tanks can fail without it due to the amount of stress on the seams, the seams aren't flexible like in glass aquariums. If you pick up a 4'x8' 1/4" thick piece of plywood you can do the back of the structure and the supports for those acrylic tanks with that one piece and kill two birds with one stone. :thumb:


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## bntbrl (Apr 23, 2009)

Would putting 4 runners from front to back remedy the floor of the tanks or does it really need every square inch supported? I would think that 4 cross peices would leave three or four inch spans. Like said, I havent owned acrylic before so I dont know. Its not that I float out dont want to put plywood under it its just that I would rather use what I have availabel than buy more stuff.

You guys think that it needs plywood onteh back for strength or aestetics?


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## Mcdaphnia (Dec 16, 2003)

Acrylic tanks do need something solid under them. A plywood shelf should do it. Plywood at the back and some on the ends is to prevent the stand from folding closed like a well-oiled Swiss knife. Screws are not dependable, especially when the load is at right angles as in this stand. Add carriage bolts to the horizontals where they cross the stand legs. Those will not be susceptable nearly as much to tearing out.


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## prov356 (Sep 20, 2006)

Those small acrylic tanks will be fine that way, and acrylic tank seams are much stronger than glass tank seams. They're not going to blow out. Fill the tank and then look under at the bottom. Unless it's a very thin acrylic, you won't see any bowing at all. Acrylic doesn't need full support on the bottom. I really don't know where that idea came from. They just need to not have spans that are excessive for the thickness of the bottom piece of acrylic. If you're concerned, then one piece added front to back in the middle would add additional support. You don't need 'full support' with plywood. And, acrylic is very flexible, btw.

Some pics of acrylic tank racks. You can't see it in the pic, but it's anchored to the wall at the end. All you need to do is anchor yours to the wall. Working around a plywood back would be a pain. Also note no full bottom support, but front to back support spaced appropriately for thickness of the acrylic bottom. And those are probably overkill for that. They're in there to prevent the front and back support pieces from moving away from each other under stress. Can't think of the term for that right now.



















That rack is fine IMHO. The bottom tanks are on the floor, no issue there. The 30 will weigh about 250 and you've used multiple lags rates at 265 plus wood screws. I don't see where the problem would be.


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## bntbrl (Apr 23, 2009)

I think I will put some carriage bolts in the supports just to be safe. Im going to see what I can find in the garage and see what I can do with that.

Prov356 are you using individual lights or are you using the room light to illuminate the tanks?


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## prov356 (Sep 20, 2006)

> Prov356 are you using individual lights or are you using the room light to illuminate the tanks?


Individual lights. I'm building simple boxes out of pine and mounting rope light LED's. You can find simple LED light strips also for smaller tanks. I use those on a few of my smaller tanks. Some don't like LED's because they're not as bright as fluorescents, but I don't like the blare of fluorescents. Just a personal preference.


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## bntbrl (Apr 23, 2009)

From my experience with LEDs you get what you pay for like anything else. There are leds that have the color range that support reef tanks. They get expensive with enough of them butthey are available. Leds use less electricity also.


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## mightyevil (Oct 23, 2008)

Prov, I don't know where the theory of supporting the whole bottom of the acrylic tank came from either but I have heard it too many times to not pay heed to it. I am afraid that with time the acrylic will bow at the bottom thus cracking a seal or something without any modification, I'd rather be proactive. At the same time you might be 100% correct and Bntbrl the acrylic tanks you've got are small and honestly I think they may be fine with a middle support from font to back but personally I'd sleep better at night supporting the whole bottom.

Like Prov said, fill them up and see if there is any bowing, though I would recommend to check every now and then because my guess is that they will, it is only a matter of time.

Prov, your fish room is beautiful! what will you be using for filtration? Are they all going to be sharing the same filtration?


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## prov356 (Sep 20, 2006)

> I am afraid that with time the acrylic will bow at the bottom thus cracking a seal or something without any modification,


It's funny, but when I built my first acrylic tank, I was thinking about putting a layer of plywood down due to all I had heard about bowing. Decided to try without. First time I filled it I sat on the floor watching the bottom waiting for the big bulge that never came. After working with acrylic tanks, I laugh at myself now for doing that. The acrylic that I used was way too thick to bulge like that in the spans that I was dealing with. It really doesn't droop and bulge like I even suspected it would. I realize now that is wasn't going to either. It would take a tremendous amount of pressure to bulge it out if the spans are small and the acrylic is thick. That amount of pressure would probably bust through plywood as well. I think it's probably easier to recommend that the whole bottom be supported than to get into calculating spans, so maybe the tank manufacturers do that, don't know. Besides, the sides almost always bulge a bit unless you go really overkill on the thickness. It's not uncommon at all. And they don't bulge more in time or give out.



> Prov, your fish room is beautiful! what will you be using for filtration? Are they all going to be sharing the same filtration?


Thanks, each rack has a sump that'll feed the two tanks above it. You can see that a little better in this pic.










Not the latest pic as I've got rocks in all of the tanks now, and am starting to put the plumbing together on one rack to test it out. My goal is operational and stocked before the end of the year.


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## mightyevil (Oct 23, 2008)

prov356 said:


> > Thanks, each rack has a sump that'll feed the two tanks above it. You can see that a little better in this pic.
> > Not the latest pic as I've got rocks in all of the tanks now, and am starting to put the plumbing together on one rack to test it out. My goal is operational and stocked before the end of the year.


Yes, I can make out the sumps now. The tanks look like 90-110 gallons each, did you make the tanks and sumps yourself?

Very nice Prov, do you have a build thread for this? I am very interested to see your progress and the equipment you are using.


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## prov356 (Sep 20, 2006)

> The tanks look like 90-110 gallons each, did you make the tanks and sumps yourself?


The tanks are about 70-80 gallons each. Including the sump, there'll be about 180 gallons in each system. And yes, I built them all.

No build thread yet, but soon. It's just been a long project with gaps in between progress, but coming together now.


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## mightyevil (Oct 23, 2008)

Wow, they look bigger, just like your 13ish gallon shellie tank (looks like at least 55 gallons). Very nice! I imagine you ship to California? Are you going to breed any Mbuna?


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## Rick_Lindsey (Aug 26, 2002)

bntbrl said:


> I think I will put some carriage bolts in the supports just to be safe.


Sounds like a good idea... based on what I can see from the picture, the only thing holding up the middle tanks are the screws attaching the horizontal rails to the legs.

-Rick (the armchair aquarist)


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## bntbrl (Apr 23, 2009)

The actuall supports for the middle tanks are screwed in with some wood screws. Then the cross block underneath those upright 2x4s are some 2x3s from front to back with 2 Spax lag screws rated at 265 pounds each, and a couple regular wood screws.

The rack I think appears to be more than strong enough. Today I put a sheet of 1/2 inch ply underneath the 30 gallon and screwed it to the supports.

Ill put some carriage bolts in and put a sheet under the bottom.

I also put some shelves on the sides of plywood with 4 scews on each side to strengthen the sway front to back just in case. 1/2 ply again there too.

I wish that I had access to lots of acrylic to amke a fishroom like that... Thats a nice fishroom setup. Mine is all cobbed together, but I have a 100 dollars int eh whole thing and is shows lol.


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