Why Does a Tank Have to be Level

[mrbill24]

Can someone explain why a tank has to be level? I've been out of school awhile, so I'm probably getting rusty. Everyone is very passionate about having a tank exactly level as not to stress the joints. If I remember, fluid at rest cannot sustain shear stress, so all the force will be normal to the panes of glass whether the tank is level or not. The hydrostatic force in a fluid of constant density is p=rho*g*h. If you tip the tank over you wind u making the tank a little deeper, but only until water starts spilling out. It looks like the only thing it would affect is the added stress due to the weight of the front pane of glass. Can anyone explain? Here is a quick diagram:

 

[Jeff]

I try and keep my tank level so the overflows work evenly. Not sure about all of your physics above lol.

 

[travis32]

I don't know that it's required to be perfectly level. Mine is around 1/8" to 1/4" off center. The tank was level before I filled it. (Has 4 legs that are adjustable on an all steel stand.)
ANd it's on carpet, with wood subfloor.

After I filled the 6ft 125g with water, it began settling... Now it's off by up to 1/4"

It's up for 4 months, as long as it doesn't fall through the floor. I don't care if it's off by 1/4" or so. I'm not going to drain it, reset the legs then fill it again. Plus, when I drain it, it may be centered again, so, it would be impossible to actually level without filling then draining then filling then draining.

I'm happy the way it is.

 

[BeanAnimal]

Can someone explain why a tank has to be level? I've been out of school awhile, so I'm probably getting rusty. Everyone is very passionate about having a tank exactly level as not to stress the joints. If I remember, fluid at rest cannot sustain shear stress, so all the force will be normal to the panes of glass whether the tank is level or not. The hydrostatic force in a fluid of constant density is p=rho*g*h. If you tip the tank over you wind u making the tank a little deeper, but only until water starts spilling out. It looks like the only thing it would affect is the added stress due to the weight of the front pane of glass. Can anyone explain? Here is a quick diagram:

A slightly out of level tank is only an easthetic issue. Tanks that have a bearing surface that is not resting on a planar support are the ones that are in danger of failure.

In the example above we can go a bit further and talk about how the load is distributed over the glass to glass joints and how those joints and the structure work to carry the load and distribute it to the bearing surface. In an "ideal" structure little would change, but the glass tank is not an idea structure and its seams and panels are also affected by gravity. But, alas if the the tank is well supported (the bottom most corner is not carrying the bulk of the weight) then it will survice just fine.

 

[mike_cmu04]

I had a 55 gal that was a quarter inch out of level leaning to the front and the bottom seam failed after a month.

 

[Swanwillow]

yeah-its not the panes, its the seals that give under the pressure



That said.. my tank is off by about 1/8th of an inch... and that's after 1/8th of an inch or more adjustments. Stupid house.

 

[BeanAnimal]

I had a 55 gal that was a quarter inch out of level leaning to the front and the bottom seam failed after a month.

The most likely cause was that the four corners of the stand were not on the same plane. That is, whatever caused the stand to be out of level also allowed it to slight twist.

 

[mrbill24]

It makes sense that an out of plane stand would not support the tank evenly. You'd wind up with at least one corner cantilevered. I can't think of an easier way to check the planarity than with a level in multiple directions.

 

[AGYDAL]

Not only consider the stress that a non level surface can cause on a tank itself....remember anything you have setting ontop of that tank (lights, canopy, glass tops etc.) will be effected too depending on how unlevel the tank is...

I had a 40gal freshwater with two big Angelfish and some darters in college...the house my roommate and I rented was a total polished turd...not a single level ceiling or floor in the place (price and location was its saving grace) the left side of my tanks water level was 1" lower than the other and it was on a flat topped desk type stand...no problems for two years TILL we left for spring break...came back to about 12 gallons of water in the tank...rest was in the carpet and somehow had managed to soak about two feet up the walling and into my roommates rooms carpeting on the other side of the wall...what we figured had happed was one of the fish bumped the intake (it had an eclipse hood) and how it was bumped the water ran between the hood and the tank rim and slowly dripped away while we were gone...luckily all but one darters survived and my old roommate and I still laugh about the landlord never finding out...but oh jeez it was a huge mess to clean up and fix the wall.

Just beware of unlevel tanks....they're are enough things beyond your control that can go wrong with this hobby...don't flirt with something that's an easy fix before filling the tank...and if the stand is one of the ones that doesn't have the center support just the ledge type thing the tank sets one don't trust it!

Think of it this way, you have a container you need to lift that has heavy stuff in it...would you rather be standing on a level floor or a hill while lifting and holding that container? The hill will cause a lot more strain on your back than a level floor would. Same with an unlevel floor with the tanks seams.

 

[eweinig]

Stupid house.

+1. My basement floor is silly out of level....

 

[Mr.Maska]

houses are level?

 

[Swanwillow]

I heard they are... I've yet to find one.

 

[opie one]

what about trying to look into a tank like the one in the diagram. ever try looking into an aquarium at a angle, it just doesnt look the same.