Leveling large tanks?

[dan2x38]

Buying a 75g Boxing Day but not setting it up right away doing my planning. Where I now have 2 x 29g is where the new 75g will be going. My 29g's are not level but I know it is not as critical as with larger tanks. I live in an older place the floors are terribly on even. How can I level the tank & stand front to back & side to side? The floors are bad. What would I use for shimming? To level one end will be well over 1/2" raise. With the 4' length it might need a lot of support in the middle?

[babblefish1960]

This truly relies upon whatever you would be utilizing for a stand for the tank.

If you use a metal tubing stand, you will have 4 distinct 1" square corners.  These are simple really, with wooden or carpeted floors, where you really are uncertain of the compressive strength of the floor, I always used round block off plates for electrical boxes, these are galvanized and strong.  They distribute the point loads of this stand from 1" square inch to approximately 12" square inches, a distinct advantage.  Then take some shims, not the cedar ones, either the preformed hard plastic ones or hardwood shims, and place these between the stand legs and the plates.  Do this carefully, and before you place water in the tank, use a good quality level. 
Check your level by flipping it over on the same surface to be sure you get the same readings on both sides, then you know it is true.
If your home is slightly old, I often lean the tank just a touch to the wall, as once you fill it with water, it may lean out from the wall depending on the resistivity of the joists under the floor.  Try it a few times and don't be afraid to take the water out repeatedly until you get it right.  Even with the worst floors, there should be one leg that needs no shimming, this will be the highest leg, and the rest of the legs have to be brought up to match.

If it is a wooden stand, or chipboard or whatever else they make them out of these days, you have two choices, place a piece of 3/4" plywood under the stand, and shim that, corner to corner same as above, however, you may want to shim the front edge and rear edge near the middle to help a bit.

If any part of my quick explanation here is unclear, do let me know and I will continue at length!

[babblefish1960]

This truly relies upon whatever you would be utilizing for a stand for the tank.

If you use a metal tubing stand, you will have 4 distinct 1" square corners.  These are simple really, with wooden or carpeted floors, where you really are uncertain of the compressive strength of the floor, I always used round block off plates for electrical boxes, these are galvanized and strong.  They distribute the point loads of this stand from 1" square inch to approximately 12" square inches, a distinct advantage.  Then take some shims, not the cedar ones, either the preformed hard plastic ones or hardwood shims, and place these between the stand legs and the plates.  Do this carefully, and before you place water in the tank, use a good quality level. 
Check your level by flipping it over on the same surface to be sure you get the same readings on both sides, then you know it is true.
If your home is slightly old, I often lean the tank just a touch to the wall, as once you fill it with water, it may lean out from the wall depending on the resistivity of the joists under the floor.  Try it a few times and don't be afraid to take the water out repeatedly until you get it right.  Even with the worst floors, there should be one leg that needs no shimming, this will be the highest leg, and the rest of the legs have to be brought up to match.

If it is a wooden stand, or chipboard or whatever else they make them out of these days, you have two choices, place a piece of 3/4" plywood under the stand, and shim that, corner to corner same as above, however, you may want to shim the front edge and rear edge near the middle to help a bit.  Should it be a quality well constructed solid wood stand, the shimming is similar to the metal stand, except that the plates aren't really required.

If you know you have 1/2" at least to deal with already, you need to stack shims in a way the keeps their surface area mostly level, that means load them facing each other point to point, it takes practice, but is much more reliable than anything else.

If any part of my quick explanation here is unclear, do let me know and I will continue at length!

[dan2x38]

If it is a wooden stand, or chipboard or whatever else they make them out of these days, you have two choices, place a piece of 3/4" plywood under the stand, and shim that, corner to corner same as above, however, you may want to shim the front edge and rear edge near the middle to help a bit.

OK Babblefish heading to get my plywood tomorrow. Having them cut it 1/4" wider all around for both the top & bottom sheets. Going with your sheet of plywood under it suggestion to level the stand. The stand has a skirt not a flat bottom. I understand shimming the front a little more to push it back towards the wall because an old place will likely sag to the middle of the floor. I do not understand why I'd shim it in the middle at the rear to help it more?

[babblefish1960]

This was advice regarding the carriage of weight more evenly over the entire footprint, the idea is to have a stable platform, if the base isn't square, even, and solid, everything that goes above has more difficulty staying safe and true.  I was suggesting securing the gaps with wedges, but if your base is strong enough to span unsupported over its entire length, than no worries.

[dan2x38]

So with a ridge base using the 3/4" plywood just shimming the corners would be safe?

[babblefish1960]

Yes.

[dan2x38]

Babblefish thanks... I secured the base with 3/4" plywood using screws & glue to hold in place. Leveled it using composite shims from Home Depot. I did as you suggested rasied the front just a slight bit more than the back. After I filled the tank the front is just a hint above level. It's been 2 days and still level and true. There was only one corner left on the actual floor that is how bad it was. With the 2 x 29s there it did not show that much. I swear one corner is at least a 5/8" lift. Now I just got to hide the handy work...

[RedFish]

Y'all should put this into the articles section, its good info!