How level is level enough?

[peerboerner]

Does anyone have an opinion (already this question sounds a little stupid) about how "out of level" a tank can be before it's an issue? I just setup my new 120 AGA, plumbed in my glorious new LifeReef Sump and skimmer and little Giant pumps, and filled it with plain water to check for leaks. The good news: No leaks, not even seepage anywhere. The bad news: The tank is ever so slightly out of level - It's obvious because the water drains from the left overflow faster than on the right, though not much faster. As far as I can tell, the stand seems level (I checked it with a level), so I'm wondering if the plastic rim around the tank, on either the top or bottom, may be glued out of level.

When I empty the test water from the tank I'll check the level of the tank bottom before filling it with new, fresh saltwater. My question, though, is: What if the tank is out of level? Should I shim the stand? the Tank? or just live with it?

Your thoughts are greatly appreciated.

Peer:(

[gregt]

Fill it with water, let it settle for 24 hours. Empty it to about 10 to 25% full and then shim ONLY under the stand. NEVER shim under the tank.

Get it as level as possible. Unlevel setup can lead to blowing a seam in the tank.

HTH,

[peerboerner]

Gregt

Thanks for the feedback. Sure enough, after I emptied the tank and checked the level of the tank's bottom, it's just slightly low on the left. To the casual observer, the level's bubble indicates level, but if you look real close, it's actually a little high on the right.

In any event, I'm going to use some door shims and carefully wedge them under various points beneath the stand on the left side of the tank. Once it's level, I'll start adding the actual saltwater slowly and check the level again at the 10% point and make additional addjustments. Since the tank has been full of fresh water for the last 2 1/2 days, I'm sure the carpet and stand have settled as much as they will... I hope.

Thanks again.

[bgdiving]

peerboerner
I would not worry too much about the tank being level from one end to the other, or from front to back most of my tanks have some sort of a slope to them. But I would worry about torque on the tank, where there might be a little bit of a twist in the stand (could even possibley be made worse with shims if they cause the stand to twist a little) I like to put styrofoam under big tanks to level out any un evenness in the stand although that will not effect slope it will eliminate most torque which is what cracks aquarium glass. A gently slopping floor just causes a cosmetic situation as far as where the water line is but an uneven floor or stand with one end level front to back while the other end slopes front to back could be very serious.:eek1:

[gregt]

Well said Brian. I totally agree, with exception of the styro helping with the torsional stress. How do you figure?

[bgdiving]

The tank and/or the stand will dig into the styro a little on the high spots thus levleing out the uneven areas if one corner wants to ride a little high the styro will compress a little on that corner rather that torqueing the tank.

It's like if you have a heal spur and stand on styro it will even out the presure spots but still support your weight and be a whole lot more comfrtable than standing directly on concrete.

My 7 ft 170 is resting on 3/4 inch styro for the past 2 years surprising how well it supports a big tank but at the same time would accomadate a significant bump in the stand or uneven edges. My first 170 (6ft) went on to a a decorative planter box and when I test filled it, as the water came to with in 2 inches of the top, it cracked (brand new tank) . :eek1: Now that could have been a built in torque in the tank as it was manufactured or it could have been related to the stand anyway the replacement tank went back onto the same planter box but with 3/4 styro under it.

[gregt]

Sorry to highjack the thread, but this is an interesting issue.

No argument that styro will "mask" a spur or small bump in the stand, but it seems to me that a difference significant enough to create a torsional issue would not be remedied by styro.

Here's my logic. It's hard to explain without pictures, but I'll try. The side that is "higher" will have a lower column of water than the side that is "lower". The "lower" side has more water, therefore is heavier, which results in more crushing of the styro, which results in an even more "unlevel" scenario, rather than the opposite.

Did I make any sense?

[bgdiving]

Sorry double post wasn't sure messages were going though.

[bgdiving]

Assuming that the tank is built square, any torsion in the stand is going to put undue strain on the the edges of the tank(thats what causes the tank to crack, as the torque builds there is increased strain on the styro, so the styro gives allowing the tank to dig in a little at the poit of most strain thrus transferring the strain into reshaping the styro rather than trying to reshape the glass box. The glass box will resist changing shape and that will transfer an uneven force into the styro at the point of torsion and the styro will give more than the glass box indenting the styro a little more at the point of the most force and you avoid an other wise nasty situation. The same also applies to the stand so the styro will work to compensate on the stand side as well as on the tank side.

Your correct on a sloping floor there would be more force on the low side of the tank because of the extra weight of the 1/4 to 3/4 inches of extra water on that end but as long as there is no torque the pressure difference would be insignificant and it would not affect the styro thus leave you with a sloping water line the styro will do nothing to correct a smooth slope and as you said could even act in reverse but so slight on the type slopes we are talking about that you would not be able to percieve the difference.

[gregt]

Ok, I see what you are saying. I'm not totally sold, but "in theory" it makes sense. Thanks for explaining.

[bgdiving]

gregt
Lets test it out at one of the next meetings, you supply a couple of identical long tanks, I'll bring the 3/4 inch styro, We'll build in a 1/2 inch torsion into stand or a concreate floor with a long incline running to one corner and we'll fill the tanks with water, with and then with out styro. Of course to be scientific we could NOT conclude anything from such a small sampling so maybe it would be better if you would bring 4 or 5 long tanks. ;)

[gregt]

You're on! ;) :D

The more I think about it the more it makes sense. Stryo would help with torsional problems if they are created due to a bad stand (IE: Not due to a poorly manufactured tank). However, it won't help with out of level situations, in fact, it'll make it worse to a small degree.

I think I'll stick to making my stands flat and leave out the styro. ;)

[peerboerner]

Thanks for the discussion and feedback.

I think I'm going to stick with my shimms, though. I placed at least 10 of them along the left side of my stand at equal amounts of insertion (if that makes sense). Thus, the entire left side of the stand has been raised an equal amount. There should be no twist in the bottom, though I don't know how I'd measure it. According to my level, the tank is now perfectly flat in both directions (left to right, back to front). I filled the tank 60% of the way with salt water and all appears to be fine.

If I manage to turn my living room into a shallow lagoon reef I'll let you know:eek1: , but I really hope it doesn't come to that. Please don't say "I told you so" if you read that post :p

Thanks again.

[bgdiving]

I live in an old house with sagging floors and my garage as various slopes = torsion, so I'll stick with using styro! Beside even if I tried to build a level stand it would not come out level any way.:D

Peer hope we didn't get too carried away in your thread and maybe answered your question or maybe just made things worse????

Time to go unpack some new coral frags that just arrived.

[gregt]

I think you'll be fine peer.

Brian. That's a great point about unlevel floors, although I hope the typical commercially built stand would be able to handle that, but who knows?

Here's a question. How could you test for this torsional problem? I was thinking that using a level diagonally across the stand would work, but if it's not under load it wouldn't really be accurate. Any ideas?

[bgdiving]

Your right with out loading you might not be able to determin how much torsion you'd have. but what I'd do is check with level front to back both sides and end to end both sides and diaganally would also be helpfull and then see if you have different angles on your level. As long as both side slope at the same direction and degree (or both ends) you will just have a water line level problem but if your slope (say length of the tank) is level or near level along the back next to the wall but slopes in ether direction along the front of the tank you would have a torsion problem then it's just a matter of degree. But as you say something that I built might not distort untill it's loaded, but you could still watch for that as your filling ithe tank in stages.

Peer Don't want to scare you with this talk of torsion and tanks cracking, you'll most likely be just fine.

Peer, By the way I sent you a PM to your message you sent me a few days ago.