Removing Tank Frame

[theamish]

Hey Everyone,
I have gone nuts over the past few weeks trying to figure a way around this but thinking about it last night it is the only logical way to have my vivarium come out right!

So I am attempting a fairly complicated landscape in my 1st vivarium(my first mistake, but once I set my mind there's no fighting it!) and I have run into a wall(otherwise known as my center brace), I have already divided the background eggcrate into 2 peices that fit perfectly which I insert on an angle but no matter what I do I cannot attach the wanted "accessories" to these walls and still get them back into the tank due to that center brace.

I posted a while ago about just cutting the center brace out because I will only have about 5 or 6 inches of water(which comes out to a max of 18.7g) in a 75g tank(48x18x22), everyone told me not to. So my next option and my real question is what do you all think about removing the entire top frame doing my work and then putting it back at the end of the build.

Has anybody done this with success, I cant find any sort of how-to on the net for installing or removing the frame. I know it cant be more then cutting some silicone but I don't want to bust it.

Secondly, on cutting out the center brace, what if I were to silicone or JB weld a peice of plexi or something back into place when I was finished? Would that suffice rather then taking apart my tank?

I am desperate for help here, my build is at a stand still and I am getting really frustrated..... Please Help!!!

Sorry about the long post all, just wanted to be clear.

[JohnEDove]

I removed the center brace from my 55 gallon so I could make a one piece lid that would fit down snug on top. Like you I only have a few inches of water in the enclosure and have had no problems related to the lack of that brace.
Of course it will never be an aquarium again.

[theamish]

JohnEDove,
Does the tank bow at all? did you fab up some sort of replacement or just leave it out altogether?

[Jason]

When i posted in the other thread about removing your C brace it was only a suggestion in case you wanted to turn it back into an aquarium and the 8" max water lvl you mentioned, the brace was added by the engineer to begin to work at 1/3 volume capacity, or so i was told. but even at 5" your still dealing with 18.7G - 160.1 pounds and at 6" 22.4g - 191.7, still to close for my comfort, but it would work either way, i just prefer the safer side of things lol, could be my OHSA training and that i help my own engineers out with structural applications at work all the time.

[froggsong]

My 36x18x17 tank does not have a center brace... It does not have water all the way to the top or anything (just a self enclosed pond atm), but it was meant to be an aquarium. I know mine isn't as big, but if it doesn't have a center brace and was meant to hold water to the top, then I wouldn't think taking the brace out of your tank wouldn't really be an issue. Does glass shatter or something when full of water if there is no center brace? I always assumed those braces were to help hold up the lid ! I guess since I am not really a fish person I just never really gave it much thought. I can tell you though, i used to have about four inches (maybe more) of water in the bottom of this tank before I decided to use a self contained pond, and while part of the bottom was land, the water was all in the substrate (this was before a FB of any type had ever occurred to me). I had about 6-8 inches of substrate in the bottom at that time, totally waterlogged, and I think it was probably heavier than just water would have been. I would think it would be more of an issue with a plexi tank, since plexi is flexible, but I really don't see what the problem would be otherwise.

[Waterkeeper]

the pressure on the sides of the tank is relative to the height of the water. at 5" of water you are below the halfway point(vertical) and still applying all of your pressure to the bottom frame, not the top one..
if i remember this discussion right from once before, structurally in a full tank, the front piece of glass has the same pressure from top to bottom( the pressure on the front pane at 16" deep is the same as 1" deep on the side walls). the pressure the manufacturer accounted for is 1/3 the volume of the actual tank. not the pressure 1/3 of the way up a full tank, because it's the same 2/3 the way up.

IMO if it was to separate at all, it would be from the bottom of the tank and *peel (for lack of a better word) upward(this is where your pressure is). maybe the engineer can interject, but i don't think you are applying any measurable amount of pressure to the seam at the top if the tank is only 1/4 full. the pressure on the silicone side seams dissipates as you move away from the water table.

[Green Ghost]

Originally Posted by Waterkeeper

the pressure on the sides of the tank is relative to the height of the water. at 5" of water you are below the halfway point(vertical) and still applying all of your pressure to the bottom frame, not the top one..
if i remember this discussion right from once before, structurally in a full tank, the front piece of glass has the same pressure from top to bottom( the pressure on the front pane at 16" deep is the same as 1" deep on the side walls). the pressure the manufacturer accounted for is 1/3 the volume of the actual tank. not the pressure 1/3 of the way up a full tank, because it's the same 2/3 the way up.

Hey Waterkeeper, what's up Good to hear from you again, bud.

My two cents on this is I'm pretty sure what Jason and you are saying is the same thing. He meant that the Center Brace only starts to serve it's practucal function as a brace after the tank is greater than 1/3 full. (Because like you said there's barely any pressure at the top with this amount of water) As for the pressure, it's true the pressure is the same on the top of the pane as the bottom (The pressure is the same as long as the top edge is on center with the botom edge.) except the bottom pane is attached to the bottom (floor of the tank) piece and so it's reinforced all along the bottom edge as opposed to the top not being attached (except to the side pieces). That makes the top part structurally weaker and more likely to break, not the bottom. If one wanted to be really precise, I guess it could be argued that in a filled tank with no Center Brace and the top part of the front and back panes bowed, then there would be slightly more pressure there than on the bottom of the pane, because the shape begins to be conical, but I digress

I've acutally built aquariums in the past. I built the two sumps I'm using here myself. (Glass shop cut the pieces for me)

In a filled 48" tank without a Center Brace (that attaches the front and back panes at the top) you can really notice how the front and back panes bow out at the top. I've seen that on some older tanks that didn't have CB's. It's not so noticeable when you look at the tank from the front but when you put a glass sliding top on it, you can see how it's not square when it's full. It bows quite a lot - maybe 1/2". You can see the stress on the pane.

Without that CB there, when the tank is filled the bowing on the front and back panes creates stress points in the glass. The glass is not perfectly uniform in that there are weaker points in it than others. Although the thickness of the glass can handle the bowing from the water pressure, if the right spot (meaning one of the weak spots) is pushed on or tapped etc.. (meaning some external force applied) then the glass can crack or break. That's why all new tanks usually come with a CB. Second reason is esthetics. The top isn't quite sqaure and glass covers don't close properly due to bowing.

Originally Posted by Waterkeeper

IMO if it was to separate at all, it would be from the bottom of the tank and *peel (for lack of a better word) upward(this is where your pressure is). maybe the engineer can interject, but i don't think you are applying any measurable amount of pressure to the seam at the top if the tank is only 1/4 full. the pressure on the silicone side seams dissipates as you move away from the water table.

I humbly disagree No way the silicone would ever peel off. I know you're not trying to say that the silicone will actually peel, you're talking about the pressure. My point is, how do I know that? Friends and I tried to move a almost half full 4ft. tank that I had built (without a CB) and it broke. The crack came down from the top not the bottom. The silicone held though, no peeling. Even afterwards when I broke off the broken pane with a hammer, the silicone was still incredibly strong.

Originally Posted by theamish

...I posted a while ago about just cutting the center brace out because I will only have about 5 or 6 inches of water(which comes out to a max of 18.7g) in a 75g tank(48x18x22), everyone told me not to. So my next option and my real question is what do you all think about removing the entire top frame doing my work and then putting it back at the end of the build.

Has anybody done this with success, I cant find any sort of how-to on the net for installing or removing the frame. I know it cant be more then cutting some silicone but I don't want to bust it.

Secondly, on cutting out the center brace, what if I were to silicone or JB weld a peice of plexi or something back into place when I was finished? Would that suffice rather then taking apart my tank?...

Anyways sorry for the long post, all that just to say that like John said at that amount of water there's no danger, the CB can be removed. I also don't see any reason why it couldn't be re-siliconed into place later on. Provided it was done properly.

[JohnEDove]

Originally Posted by theamish

JohnEDove,
Does the tank bow at all? did you fab up some sort of replacement or just leave it out altogether?

I just left it out all together and have no bowing. Of course it will never be a crayfish aquarium again but so what, I don't keep crays anymore.