Acrylick thickness and reinforcement options for very deep aquarium

[pavel100]

Hi everyone,

I am new here and would tremendously appreciate help on an acrylic thickness and reinforcement/division problem for a very deep aquarium.

At the bottom of my post I have collected some links that may be of help for people looking for acrylic thickness for also deep aquariums - my conclusion is that the San Diego plastic thickness calculator appears to be one that people broadly follow: http://www.sdplastics.com/aquaria1.html

This is a big problem for me as this means my already owned acrylic window due to its huge depth and length would not work:

I have a 14' long, 3' aquarium enclsosure with a flexible height of a minimum of 7' but as the enclosure reaches all the way up to the floor above the height of the aquarium can be up to 10' (preferred).

The tank is built with concrete (blocks on the outside and in addition 4'' cast concrete) - that should be safe.

Already a while ago I purchased a 72'' inches high and 13' long cell cast acrylic panel of 2'' thickness to install as a window and it is actually already in place just about one foot from the bottom. My water volume is just about 2000 gallons.

When I enter 72'' height, 156'' length and “yes” for top closed (even though it is actually open, I consider the concrete structure sound enough) the result is that I would need over 3.5'' acrylic but I only have 2''....

My questions are:

1) Does that mean that I cannot fill the aquarium to the top of the glass or is there still a chance? I read many times that when not the whole aquarium is out of acrylic but only one side panel, the safety requirements are lower. I also read that the plastic manufacturers have huge safety margins in their calculators, so I still have a bit of hope.

2) If I am doomed, can I subdivide the panel still? According to the Sand Diego plastic calculator a panel of only one third the length but the same height would be ok with 2''. But as the glass is already in place as one piece, can I just put for instance a wood frame inside and/or outside the existing glass and maybe seal around it – would that qualify as different panels then? I also read many times about vertical braces – how would they work or help me here? What is the easiest way to put them on an existing acrylic panel? I would not like to drill the concrete structure much though.

3) Are there any other ways to reinforce an existing acrylic sheet (e.g. transparent security foil or so)

4) Are there any other ways to reduce water pressure inside the tank. What about one foot of sand at the bottom of the aquarium – would the water pressure inside the sand still be the same as above the sand even though most of the water is displaced there with sand.

Any help would be very much appreciated.

Pavel

-------
Other monsterfishkeepers-users used or planned with the following acrylic thicknesses in their aquariums:

36'':
- about 13/16'' reported as properly workable with bowing but 1'' reported as recommended: http://www.monsterfishkeepers.com/forums/showthread.php?t=343098&highlight=acrylic+thickness
- discussion if 1/2'' or 3/4'' can work or more thickness is needed. 3/4'' considered workable with bowing: http://www.monsterfishkeepers.com/forums/showthread.php?t=272192&highlight=acrylic+thickness

48'':
- with only 1'' acrylic, working with slight bending: http://www.monsterfishkeepers.com/forums/showthread.php?t=359819&highlight=acrylic+thickness
- 1.88" recommended in this post: http://www.monsterfishkeepers.com/forums/showthread.php?t=336234&highlight=acrylic+thicknes)
- 2'' acrylic used here: http://www.monsterfishkeepers.com/forums/showthread.php?t=275939&highlight=acrylic+thickness

57'':
- 1.5'' acrylic, reported as on the safe side / slight overkill (http://www.monsterfishkeepers.com/forums/showthread.php?t=45035&highlight=acrylic+thickness)

60'':
discussion on thickness tending towards 2.5'' as "more than fine": http://www.monsterfishkeepers.com/forums/showthread.php?t=254369&highlight=acrylic+thickness

180'':
4.5'' discussed without conclusion:
http://www.monsterfishkeepers.com/forums/showthread.php?t=192744&highlight=acrylic+thickness

 

[Pharaoh]

The material from which the tank is made is really of no consequence when calculating the thickness you will need for the front panel.

To answer your questions;

1. with just one panel, I do not think it would be wise to fill the tank up completely. You would be drastically under the safety limit.

2. Yes, subdividing the panel is an option. You could keep the panel in a full sheet with additional bracing and it would work. Since your doing a concrete tank, you could use wood or add in a concrete vertical brace.

3. Not that I am aware.

4. The only way to reduce the water pressure on the panel is to decrease the height of the viewing window.

Here are a few of the numbers that I ran for your tank.

1 window - 156 x 72 = 3.94
2 windows - 78 x 72 = 3.07
3 windows - 52 x 72 = 1.95
*this is a rough guess, the windows would probably be smaller depending on the thickness of the braces and what not.

Now, I will put a disclaimer on this. There have been many tanks that have been built using thinner acrylic that what is listed on the calculators. For example, I have a 96 x 24 x 30 300G tank that is made from 1/2" acrylic, but the calculator says you need 1.11. You can forgo a bit of the safety factor to build this, but there is no real way to calculate the safety factor on acrylic like you can on glass. I'm not saying that you can't go thinner, but it us to you to take on the risk.

 

[Ocean Railroader]

I'm right now checking the costs on a four foot tall wide eight foot long two inch thick sheet of plan new Aclyric sheet for $1300 dollars for a cement or cinder block fish tank idea that is giong to be eather eight feet by feet or ten feet by ten feet. Would two inch thick acylic be strong enought to hold back four to five feet of water on a viewing window for a cinder block fish tank?

Also how thick would the acylic have to be for a five or seven foot deep cement ffish tank viewing window?

 

[Pharaoh]

I'm right now checking the costs on a four foot tall wide eight foot long two inch thick sheet of plan new Aclyric sheet for $1300 dollars for a cement or cinder block fish tank idea that is giong to be eather eight feet by feet or ten feet by ten feet. Would two inch thick acylic be strong enought to hold back four to five feet of water on a viewing window for a cinder block fish tank?

Also how thick would the acylic have to be for a five or seven foot deep cement ffish tank viewing window?

2" thick acrylic should work for your first measurements.

You would need about 3.5" for a 7 foot tall tank.

 

[Ocean Railroader]

Thanks
I think any thing over two inches would have to be custom made at the factory. The man at the factory said that four by eight sheets of acrylic was about the biggest they had in their regular made sheets.

 

[quovadis]

I hope this will be some sort of consideration in your case ,,,I have a 7 by 7 with a depth of 9 feet centrally connected with a viewing port of 6 by 4 by 3/4 glass<<it seems to be holding very well considering the stock i have in there/// although i wanted to use something a bit ticker ,but it was just not available in this part of the world ,

 

[pavel100]

Just wanted to say thanks to Pharao for the helpful reply on my questions. I will try the 3 vertical braces (though it will be tricky to cast more concrete without messing up the acrylic sheet but will have to find some way somehow).

 

[Pharaoh]

I hope this will be some sort of consideration in your case ,,,I have a 7 by 7 with a depth of 9 feet centrally connected with a viewing port of 6 by 4 by 3/4 glass<<it seems to be holding very well considering the stock i have in there/// although i wanted to use something a bit ticker ,but it was just not available in this part of the world ,

That seems a little sketchy to me. 3/4" is really pushing the safety factor.

 

[Ocean Railroader]

quovadis could you post a few photos of your large tank on this thread?

I'm woundering that if I get the right Acrylic for my ten by ten seven foot deep cinder block fish tank idea. I'm worried about how would I be able to build the over head steel frame that would go over top of the acrylic wall that would help hold in the viewing plannel?

Also how does adding the viewing planel work? Do you glue it on top the cinder blocks and pound armor? Or do you build a grove around the viwing window that allows the Acrylic sheet to fit into the grove and then the grove and the cinder blocks hold the viewing window into the side of the fish tank?

 

[pavel100]

Sorry, I would like to ask your guys for your opinion once more: I am just planning to put 2 braces on my 13' wide and 72'' high 2'' thick acrylic panel. I want to use 4'' by 4'' cast concrete with steel rebars in the center as the brace. Do you guys believe it would be sufficient to have these braces only on the outside (cast directly next to glass and thus preventing bowing as I assume)? Or would an effective brace also require something on the inside of the tank? Thanks!