Tank Stand for Two 55 Gal. Tanks

my guess

As the son of an engineer, I can give you a moderately informed opinion. In short, two 4x4s should be able to carry 650 pounds across 48". I am not sure how you are supporting the ends of the top tank, but as long as where the 'beam' connects to the 'column' is sound, 4x4s can carry the weight. 2x6s on edge might be even better.

The way I reason these things (since dad is no longer around to calculate it for me) is to imagine large people standing on it. Many people have large decks and a half dozen large adults can stand in one area supported by 2x6s without risk of falling through. All you are asking is to have one 4x4 carry two midsize adults spanning 48" - no problem. Wood can be pretty strong. If you buy construction grade lumber, be aware that it may deflect as is dries out indoors. If there is any bow to the wood, use it by placing the bow upwards like an arch. If you DO decide to use a third board, make sure they are all exactly flat and even or else one board will not carry any weight anyway.

Yes, I meant warp when i said deflect. Actually warp is the better word here; deflect is what happens under load whereas warp is a relatively permanent bend.

And I retract what I said about placing any bow into an arch-like shape. You need a perfectly flat board, period, to even out the load, so only use flat boards. But I have little doubt about 4x4 lumber carrying your load over 4'

Tom
hobbiest woodworker

sounds like over kill.I use 1x8s rails and 2x2s for the up suports very sturdy.
The cinder blocks scare me as they can explode/crumble this is why you dont use them for working under your car I have had them fail under 1000 lbs load and a twin 55 stand will carry more weight than that.

I'd put a piece of plywood between the tank and the 4x4's But maybe you were already thinking that and just didn't say it.

here is a real easy sturdy stand I made years ago looks kinda crapy now 5 moves and moved like 15 times in house.

This was very simple I used deck building hanger joists (outlined in red)and all 2x4s once you have the hangers set it kinda snaps together then you add as many screws as you have around.This was the easyest one I made and hands down the sturdyest.Cost was $13 painted unless you have the block and 4x far cheaper.

I've made all-wood stands and cinder-block-and-wood stands, usually for 75 g tanks. I can't imagine the weight from a 55 (or a 75, for that matter) shattering a cinderblock. At most, a filled 55 would weigh in at 600 pounds; divided across 4 cinder blocks, that's only 150 per that each block must support. You'd have to have a pretty punky cinder block to disintegrate under that load. If one was really worried, you could lay the cinder blocks horizontally and disperse the load somewhat through more walls of the block. I personally wouldn't lose any sleep over it.

The only problem with I could see would be if you didn't support the ends of the tank. I have found it to be quite easy to make, out of 2x4s, frames that match the size of the tank's footprint. That way, all the outer edges are supported. I apply a couple of strips of high-density, adhesive-backed weather stripping foam to each surface the tank will rest on, then I cut a piece of corrugated cardboard to sit on top of the frame, and then the tank rests on top of the cardboard. The foam and cardboard take care of any slight high spots that might be present, and then you can level the whole tank-frame unit on top of the cinder blocks. If you try to level the tank using just two 4x4 runners, I'd be concerned out the runners not be exactly the same height, etc. The last thing you want is for their to be any racking (twisting) in the frame your tank is resting on.

I much prefer builing all wood stands, because you don't lose so much floor space to bricks, but the cinderblock method is quite a bit easier and quicker.

Sorry for the lengthy post...

Jim

cinder blocks are very sturdy dont get me wrong but when used for a aplication other than block mortar block they cant take much weight unless the load is aplyed in to the top of the horizontal layed block and the load must span the entire block to even come close to the factory specs for load.Useing on end or even useing the holes is asking for trouble.Take a block and and break take the same length 2x2 pine board and try to break it in 1/2 let alone in to 100 pieces.I personaly have seen block fail and its not ever cheap or fun.
If anyone cares I'm building a canopy and stand for a new 55 tonight and will take step buy step pics to post latter.
BTW I make stands useing a cheap drill,and a circle saw no fancy wood tools needed me I even made one with out a tapemeasure in fact it was the black one I posted.