Tank stand top not fully level

[CaptainKiwi]

I have just finished building a stand and have found that the top isn't quite level - it's about 3-4mm off. Will a 50mm EPS board on top of the plywood allow for these small deflections to level out?

 

[ndrwater]

What type of tank is this? Glass or acrylic?
Not to be alarmist, but 3-4mm in +/-8" (torpedo level) COULD be quite a lot. If the tank was 8' (244cm) I would be concerned enough to make sure everything was as close as possible to level.
EPS could take up the space, but gravity works down at an equal rate. Acrylic tanks need a solid level surface under the entire bottom of the tank so there isn't undo stress places in places you dont want. Like seams..
Glass tanks, depending on the construction, rely more on perimeter support so you could shim the low spots.
If the entire stand is leaning, I would fix it to be as level as possible with shims

 

[CaptainKiwi]

What type of tank is this? Glass or acrylic?
Not to be alarmist, but 3-4mm in +/-8" (torpedo level) COULD be quite a lot. If the tank was 8' (244cm) I would be concerned enough to make sure everything was as close as possible to level.
EPS could take up the space, but gravity works down at an equal rate. Acrylic tanks need a solid level surface under the entire bottom of the tank so there isn't undo stress places in places you dont want. Like seams..
Glass tanks, depending on the construction, rely more on perimeter support so you could shim the low spots.
If the entire stand is leaning, I would fix it to be as level as possible with shims

The tank is rimless and made from glass, the dimensions are 180cm long x 55cm wide x 40cm high. The stand itself isn't leaning and the top is flat, it's just very slightly sloped if that makes sense

 

[UncommonSense]

The tank is rimless and made from glass, the dimensions are 180cm long x 55cm wide x 40cm high. The tank itself isn't leaning and the top is flat, it's just very slightly sloped if that makes a difference

As long as the top is perfectly flat (plane), and there is no risk of it sagging/bowing over time (poorly fitting structural lumber); there’s no reason why you can’t just carefully shim one side until the top of the stand is level!

— just note that a tank this long should always have six points of contact with the ground at dead minimum! (Don’t ask me how I know!)

— the above advice assumes you are placing this tank on a relatively non-compressible surface, such as concrete, or tile over concrete!

 

[CaptainKiwi]

As long as the top is perfectly flat (plane), and there is no risk of it sagging/bowing over time (poorly fitting structural lumber); there’s no reason why you can’t just carefully shim one side until the top of the stand is level!

— just note that a tank this long should always have six points of contact with the ground at dead minimum! (Don’t ask me how I know!)

— the above advice assumes you are placing this tank on a relatively non-compressible surface, such as concrete, or tile over concrete!

The tanks going to go on a wooden floor but I will make sure I have lots of points of contact! I'm currently trying some shims out and the tank is waaaaaay less level then I thought - just using thin wooden coasters to get an idea and pretty much every corner will need a little shim to even it out. I am slightly worried the bottom of the tank won't make full contact with the floor below and since this tank is going upstairs I would like to make sure the contact with the floor is as even as possible. Will this be ok?

 

[ndrwater]

since this tank is going upstairs I would like to make sure the contact with the floor is as even as possible. Will this be ok?

Should be with the shimming you mentioned. As mentioned above, many points of contact, and being rimless, I would get it as close to perfect as you can.

 

[Patx]

Just like refractometer... sometimes level are way off.
Small plastic one are the worst.

 

[UncommonSense]

The tanks going to go on a wooden floor

since this tank is going upstairs I would like to make sure the contact with the floor is as even as possible. Will this be ok?

this complicates things!

So, between tank, sump, stand, water, and sand/rock; this system is nearing 1,000kg (~2,200lbs) in total weight when up and running….

Care will need to be taken to ensure that the long span of the tank is oriented perpendicular to the flooring joists, vs. parallel! — in addition, a careful structural assessment should really be made to ensure this floor can support such a vast weight! (Particularly if you live in an earthquake zone!)

Once structural concerns are out of the way; another concern with wood flooring is stand leveling feet or similar small-footprint contact patches pressing into the floor! — these can physically indent the wood flooring over the years if the number of contact patches is too few, and/or contact patches have a small footprint!

— (Math I did somewhat recently put a ~1,700lb tank at under 90PSI on the flooring with six leveling feet of 2.625” [66-67mm] footprint diameter, for reference/context!)

 

[CaptainKiwi]

Should be with the shimming you mentioned. As mentioned above, many points of contact, and being rimless, I would get it as close to perfect as you can.

Interestingly, putting some large weights on the bottom of the stand seem to do quite a lot for the levelling, do I account for this with the shim?

 

[CaptainKiwi]

this complicates things!

So, between tank, sump, stand, water, and sand/rock; this system is nearing 1,000kg (~2,200lbs) in total weight when up and running….

Care will need to be taken to ensure that the long span of the tank is oriented perpendicular to the flooring joists, vs. parallel! — in addition, a careful structural assessment should really be made to ensure this floor can support such a vast weight! (Particularly if you live in an earthquake zone!)

Once structural concerns are out of the way; another concern with wood flooring is stand leveling feet or similar small-footprint contact patches pressing into the floor! — these can physically indent the wood flooring over the years if the number of contact patches is too few, and/or contact patches have a small footprint!

— (Math I did somewhat recently put a ~1,700lb tank at under 90PSI on the flooring with six leveling feet of 2.625” [66-67mm] footprint diameter, for reference/context!)

For my particular setup I have planned as much as possible and have managed to get the weight to a bit under 700kg (water weight 380, tank 80, rock 30, sand 20, stand 80, sump 80 for a total of 670) - heavy but slightly more reasonable! It's of course going parallel to joists and the wall it's up against is load bearing and has 2 steel beams designed to support the top floor and the roof - given the spacing of my joists, at worst each joist will bear 200kg, 670kg across 4 joists is 167kg and across 5 is 134kg (I will be going across 4.5) Again, definitely on the heavier side and I will be measuring the floor to make sure there is no deflection, but given this is a new build it's a risk I'm comfortable with, thought I definitely won't be going even a little over volume

If I got say 5 level feet across the long side and 3 across the short, would that help fix my levelling issues and make sure it's properly supported?

 

[UncommonSense]

If I got say 5 level feet across the long side and 3 across the short, would that help fix my levelling issues and make sure it's properly supported?

This will work! You’ll just need some additional leveling feet under the stand, near the center/under any load bearing columns to keep the center of the stand from bowing with offset sump weight/etc…

— these center leveling feet can be a real pain to get to, so plan accordingly and make a tool to adjust them with minimal working space, if need-be!

— once you’re completely satisfied with how the stand is leveled, add the tank to it and check level again with the additional weight making everything settle…

— check level again during the filling process just to be sure your floor joists aren’t deflecting appreciably!