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View Full Version : Leveling and large tanks


jccaclimber
09/15/2016, 11:14 AM
I have a roughly 580 gallon glass tank sitting in my back yard waiting for me to repair the overflow and a significant corner chip. Unfortunately I did not get the stand, and will be building my own. This won't pose an issue (although advise is always appreciated), I've already done that for my 300 acrylic (fresh) and 170 gallon glass (reef) tanks.

This tank will be a good bit heavier than the others, which got me wondering about "level". Fortunately my house is on a slab, so I think I'll be ok there.

I can level the stand when empty, but I'm sure that putting a 5,000 pound object on top of the stand will make it move a bit between the supports. What do people do to make sure the tank is still evenly supported after filling? It seems like there must be more to uniform support than just being level at the ends and using some foam.

*Note, I recently leveled a large lathe where 0.00005" per foot was considered too much, so I might be over thinking this.

dave.m
09/15/2016, 08:49 PM
If it's the floor you're worried about you can build a temporary dam and pour some levelling compound in it. If it's the stand you're worried about you can easily start to load as many heavy objects as you can lift onto the finished stand to see how it behaves.

Dave.M

Flagg37
09/15/2016, 09:05 PM
*Note, I recently leveled a large lathe where 0.00005" per foot was considered too much, so I might be over thinking this.

I'm sure if you level it to 0.00006" per foot you'll be fine. Seriously though, being level is great but I think being flat is more important. Make sure there's no high points. If there's any bowing or cupping or twisting of the top of the stand it will produce stress. I scribe the bottoms of my stands so that any variation in the concrete is taken up and it's supported all the way around.

jccaclimber
09/15/2016, 09:49 PM
I'm sure if you level it to 0.00006" per foot you'll be fine. Seriously though, being level is great but I think being flat is more important. Make sure there's no high points. If there's any bowing or cupping or twisting of the top of the stand it will produce stress. I scribe the bottoms of my stands so that any variation in the concrete is taken up and it's supported all the way around.

The idea is that if you sweep a level of that type over the surface that it is also close to planar. It was just an example though, plywood unless surface ground isn't nearly smooth enough to take a reading of that accuracy. You did hit my point though, it may be level under light load, but who knows how it will bow or twist under load. It might be touching, but not supporting at multiple locations since it is effectively statically indeterminant.