Varied acrylic panel thickness?

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DarylMac

DarylMac

Piranha
MFK Member
Oct 22, 2016
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hey all,

One day in the future I may try building an acrylic aquarium.

Dimensions will likely be 8 feet long, 2 feet wide, and less than 2 feet tall (probably more like 21" to 23" tall, with water line being about 1" below the top).

I was thinking of using 3/4" acrylic for the front and back panels.

Would it be okay to use 1/2" thick panels for the bottom, top, and end panels?

Rather than using strips of acrylic to make a eurobrace I was planning on using a single panel of acrylic and cutting the openings out of it (I've read that is stronger).

Thank you in advance!
 
Hey, I'm no expert, but here's what I see...

Home aquariums with thinner acrylic exhibit more bowing, and craze sooner/more.

Public aquariums use overkill thicknesses and a) don't have to brace, and b) don't show crazing.

We just visited our local public aquarium today. Even the smaller tanks were 2" acrylic...but they needed little or no bracing, and were crystal clear down the entire length.

I'd say that acrylic thickness is one area of a custom build that you legitimately want to go overboard with. In the long run, it's an expense that will pay itself back in optical quality many times over.
 
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Lots of people are building 8x2x2 out of half inch. You should be fine for the most part. Make sure the full bottom is completely supported. Your top will quite possibly do some things over time you'll notice. The shorter in height you build your tank the better, less water pressure. I've owned several of the old 125s - 72"x18x20 tall. Those were made of 3/8th (or thereabouts) and bowed noticeably front and back, the tops seemingly puckered upward a bit near the openings.
 
We could type back and forth every few hours for the next few days. Or you can just read this: https://www.reef2reef.com/threads/acrylic-fabrication-q-a.224773/

I'm going to try and talk him (Floyd) into coming here and making a similar thread, although it looks like he's busy building algae scrubbers these days. Or once I get my technique tighter and my confidence up I'll attempt a thread here someday in the future.

That's everything you ever needed to know about building an acrylic the right way. I would use 3/4" all the way around and use the pin/shim method with custom solvent: methylene chloride 95% glacial acetic acid 5% as opposed to weldon 3 or 4. 40 seconds before pulling pins. you'll understand once you read the thread. Definitely go just under 24" to save on total material sheets. With the blade kerf you'll use extra sheets unless you sacrifice a little under 24" as the sheets are 96" x 48"

Use Arkema PMACS, or their "A" grade product plexiglas G. Spartech (Polyone) Polycast is the best but $. I wouldn't recommend any other brands of acrylic these days, but some guys still like chemcast and acrylite.... but it's all in the thread.
 
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Thanks everyone for chiming in. Dieselhybrid, I've started reading that link - thank you.

Perhaps an explanation on why I am asking this:

I've done some reading and watched a few videos. I'm familiar with the methods used for assembling the tank; including the pin method or capillary action (for thinner sheets).

I've also used some calculators and know that I should be good using 1/2" for everything, provided the tank is braced, and I stay under 24" height.

I'm also rounding off my numbers here, but I am keenly aware of saw kerf and the effect it can have on a project if you don't plan for it (I do some woodwork in my spare time).

I've also started making some calls to price out sheets of cell cast acrylic. I called one local retailer to inquire about pricing for materials.

Apparently I can get sheets as large as 120" x 48" (10 x 4). There is a big increase in cost to go to this size sheet over a standard 96" x 48", but the price is such that buying 1 sheet of 10x4 1/2 acrylic and 1 sheet of 8x4 3/4 inch acrylic would be the cheapest way to built the tank.

According to a panel optimization program I used this would also give me all the material I need with little to no waste in off cuts (only losing the kerf).

Basically if I cut 2 feet off the length of the 10 foot sheet I can make the top & bottom out of the 8 foot section, the two (24" x 24") ends out of the off cut, leaving the sheet of 3/4" material to be split for the front and back panel.

I am presuming that the 3/4" material on the front and back panels would help reduce bowing. I'm also thinking that reducing the height of the tank by an inch or two would help with that as well.

Even though I have read that you can use the capillary method for material 1/2" and less, I was planning on using the pin method all the way around, at this point.

Even trying to minimize waste and eliminate having to purchase a 3rd sheet of material altogether, the cost to build this will still be pretty high. Want to make sure my being "thrifty" isn't going to lead to problems later on.
 
My understanding is that 3/8" inch acrylic (from reading, not building or using) is a dubious choice for a tank top due to warping issues. As in, you may have to flip it every couple days to keep it flat.

It could be that you won't see this issue with 1/2" or that you have alternative methods to keep it flat. I'm not saying 1/2" won't work fine as I've never seen any comments about 1/2".

Just an FYI.
 
The top sheet of 1/2" would be welded to all 4 sides, all around the perimeter.

I would cut the access panels out of this top brace and router a bevel on the openings.

The "lids" could be made from a different material entirely that is less prone to warping. I think it is lexan? I'm not 100% sure, but I just heard of this from watching a video from Aquarium Co-op on Cories new 800 gallon tank... I also like the idea of routing in some of the ports that he had installed...
 
In the thread posted above:

"Here is my general philosophy. I try to stay conservative.

Minimum material thickness: 1/4" (0.236). I never use anything thinner, anywhere.

Preferred material minimums: 3/8" (0.354) for vertical exterior walls, 1/4" for top and bottom panels. For interior baffles, 3/8" for pressure baffles (water level is different / lower on one side), 1/4" for non-pressure baffles.

Display Tank Material Thickness

This general guideline is what James relayed to me as his personal guideline. I believe these are based on Polycast, which is imperial thickness (1" = 1.00") so keep that in mind when using a metric-based material.

For a EUROBRACED tank:
24" high, use 1/2" minimum
30" high, use 3/4" minimum
36" high, use 1" minimum

Eurobrace minimums:
3" perimeter eurobrace on any tank.
6" wide crossbrace for every 24" of tank length.
1.5" radius for all interior corners of the eurobrace cutouts (3" diameter circle). This is very important.

For instance:
A 48" x 24" tank (footprint) will have 3" perimeter eurobrace and a single 6" crossbrace at 24".
A 72" x 24" tank will have 3" perimeter eurobrace and a two 6" crossbraces, one at 24" and one at 48".

At 8' length, it's recommended to jump up one material thickness* to keep deflection down."
 
One thing I have to say is that I'm extremely conservative with risk taking in regards to my stock. So I am projecting those values onto this discussion.

Your tank will be eurobraced and 24" high so yes 1/2". However at 8' you go up a size putting you at 3/4"

Another factor to consider is that if you aren't ordering the most expensive brand, Polycast by Spartech (polyone) your material isn't really a true .5". (that's the only brand in imperial thickness under 1") It's only .472". (All other brands are in metric at this thickness) Doesn't sound like much difference sure... But when you're already supposed to jump a thickness to .750" only being at .472" becomes relevant. Especially in 5 years, 10 years and beyond.

I have read that if you want to skimp, which is something I clearly will never endorse in life, that the bottom panel and sides are where it is often done. The top panel is essentially what's holding the box together. I've read not to skimp on thickness there.
 
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Okay i sent a message to a builder on another forum. He corrected me, he said never skimp on vertical panels only top and bottom. Although he said not to skimp at all :)
 
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