Acrylic to Plywood

[AlexG]

I agree 100% on the plywood tank concept. The cost of marine grade and proper epoxy and all the potential problems would leave me sleepless at night. What about the worms that can bore right into the wood with no problem...yikes.

Make sure the acrylic panels are of the required thickness to prevent flexing and make sure the rebate is completely rigid. That is why public aquariums use concrete with a metal rebate with a metal back plate bolted around the acrylic and wet set silicone for large panels. I personally would never use this technique and build the entire tank out of proper acrylic panels. I would not pretend to be able to pull off a million gallon aquarium like the Outer Bay Exhibit in California. Acrylic panels were 12 1/2" thick and butt seamed on site for that display. If you are observant you can see the seams due to light transmission. Impressive build.

From my perspective the plywood tank offers some cost benefits if the tank is the right size. I did not use marine grade plywood due to the chemicals used for making it marine grade. The epoxy cost is not that bad depending on the size of the tank. If I were to go bigger than my current build (480 & 720) gallon tanks. I would use reinforced concrete and still use an epoxy sealer. The viewing windows are the concern as acrylic can be cost effective but difficult to seal without the proper knowledge. I am going with glass for my plywood build as it is not nessarry to order glass over a standard size. From a difficulty standpoint a plywood tank takes time and patience to build. It is not a fast process and the structure needs to be evaluated. There is information on building plywood tanks but I over built the recorded standards as I would rather over build than under build an aquarium. I know there is risk with a plywood aquarium but I have accepted the risk and I believe that with the proper construction it is just as safe as an aquarium made from glass or acrylic. I guess when I get the tanks up and running it will be the true test but I don't think it is a poor method of building an aquarium as the freshwater community has had success building very large plywood aquariums for decades. I think that the build in this thread can help to share knowledge if it is successful or a failure as that is the only way to learn.

 

[Lowell Lemon]

I wish you well AlexG on your build. I am just lazy and tend to rely on 30 years of acrylic experiance since it is easy for me and I have all the equipment. I did not intend to slight your adventure just guess I am amazed by the expression of experimentation that I have lost over the years. I would not start production of glass tanks at this point but I sure would own them and sell them in smaller sizes. I have seen pictures of many plywood and fiberglass tanks over the years and even had one at one time. I do like your design and want to see it successful and completed. It would make an amazing display. Wish you well and I am following along.

 

[ScottF83]

Plywood because of the size and custom shape.

Many people have built plywood tanks without worms boring holes through the entire way...

But that wasn't really the point of this thread, it was to ask how to set an acrylic panel.

If there is no answer then I will be forced to use glass, I guess.

Will also look at the cost of a fully custom acrylic piece. Probably at least twice the price! GulpGulp.

 

[AlexG]

I wish you well AlexG on your build. I am just lazy and tend to rely on 30 years of acrylic experiance since it is easy for me and I have all the equipment. I did not intend to slight your adventure just guess I am amazed by the expression of experimentation that I have lost over the years. I would not start production of glass tanks at this point but I sure would own them and sell them in smaller sizes. I have seen pictures of many plywood and fiberglass tanks over the years and even had one at one time. I do like your design and want to see it successful and completed. It would make an amazing display. Wish you well and I am following along.

Thanks for the confidence boost. No harsh feelings intended. I guess I just find that it was a good solution for my build. I think acrylic is a great material for aquariums i just don't like how easy acrylic scratches.

 

[ScottF83]

I wish you well AlexG on your build. I am just lazy and tend to rely on 30 years of acrylic experiance since it is easy for me and I have all the equipment. I did not intend to slight your adventure just guess I am amazed by the expression of experimentation that I have lost over the years. I would not start production of glass tanks at this point but I sure would own them and sell them in smaller sizes. I have seen pictures of many plywood and fiberglass tanks over the years and even had one at one time. I do like your design and want to see it successful and completed. It would make an amazing display. Wish you well and I am following along.

lWell exactly... If it starts springing leaks left right and centre I will just have to switch to an all acrylic or glass affair. Hopefully that will be at least two years down the road post-build! but as Alex says, I've also seen many builds using ply over the reasonably long term. But how long do we keep a tank before changing again? lol

Anyway, will keep looking for a clear and tested acrylic window method that I can utilise in my design

 

[ScottF83]

Thanks for the confidence boost. No harsh feelings intended. I guess I just find that it was a good solution for my build. I think acrylic is a great material for aquariums i just don't like how easy acrylic scratches.

Seconded, no animosity from me. Still in my research stage!

 

[AlexG]

Seconded, no animosity from me. Still in my research stage!

I would look for more glass suppliers. Even an aquarium builder for glass. The quotes I got from local glass suppliers were quadruple the quote I got from an aquarium builder. I don't understand why this was the case in the states but all I can figure is the shipping costs of glass. It comes down to evaluating risk over cost. If there is no easy or known solution it might be better to spend the extra money on glass or a re-design might be needed. I originally was going to make one of my plywood tanks 4' deep but that was too risky due to the structural requirements. When deciding to build a tank on your own the risks are more apparent. Planning over anything else is key. Since I am building in a basement a leak or catastrophic flood will cause far less damage. I think the build in this thread is a great build that can really highlight the potential of a plywood build. It seems that sealing acrylic to plywood is a challenge that involves a risk of failure. It is understandable that sharing methods of this type of seal can have legal reasons for being hesitant to share information. Water damage from a failure on an aquarium can cause damages in 10s of thousands of dollars or more.

 

[ScottF83]

I would look for more glass suppliers. Even an aquarium builder for glass. The quotes I got from local glass suppliers were quadruple the quote I got from an aquarium builder. I don't understand why this was the case in the states but all I can figure is the shipping costs of glass. It comes down to evaluating risk over cost. If there is no easy or known solution it might be better to spend the extra money on glass or a re-design might be needed. I originally was going to make one of my plywood tanks 4' deep but that was too risky due to the structural requirements. When deciding to build a tank on your own the risks are more apparent. Planning over anything else is key. Since I am building in a basement a leak or catastrophic flood will cause far less damage. I think the build in this thread is a great build that can really highlight the potential of a plywood build. It seems that sealing acrylic to plywood is a challenge that involves a risk of failure. It is understandable that sharing methods of this type of seal can have legal reasons for being hesitant to share information. Water damage from a failure on an aquarium can cause damages in 10s of thousands of dollars or more.

Exactly Alex, agree on all points.

Since my last post, I've ridden about 150 miles on my motorbike and had time to think

A drip panel made of waterproof ply will be under the tank now which will support the load across the floor joists and also have a subtle lip to direct any leaking water to a hole in the wall that leads to the garden. Also been considering making the tank out of acrylic more and more, which is a shame in one respect as I like this challenge but...

Glass £1000 plus ply, 4x2 wood, epoxy stuff, glue stuff, screws, etc etc

Or about £600 for acrylic sheet plus all the same

Talking about £1500-£2000 for ply option... SooooSo ooo.....how much for allall acrylic? I will have to find out! Will still be the same shape.

 

[norskfisk]

But first... my question... how do you attach an acrylic 25mm sheet to a plywood aquarium?

That is very hard to do. I don't have experence with acrylic, but I have seen some advice from people in the know. The problem isn't just that silicone or other sealants won't stick. That is the smallest part of the problem. The big part is that when acrylic gets wet on one side and not on the other, enormous warping forces work on it because there is more water in the wet part of the panel. Even tanks that are weld glued properly can split apart if there is no euro bracing. Try searching for "acrylic warping" and "acrylic tank without eurobrace". I saw a nasty case on a british forum where a guy had his 1" home made sump split in the seam. User name was xdave.

 

[ScottF83]

That is very hard to do. I don't have experence with acrylic, but I have seen some advice from people in the know. The problem isn't just that silicone or other sealants won't stick. That is the smallest part of the problem. The big part is that when acrylic gets wet on one side and not on the other, enormous warping forces work on it because there is more water in the wet part of the panel. Even tanks that are weld glued properly can split apart if there is no euro bracing. Try searching for "acrylic warping" and "acrylic tank without eurobrace". I saw a nasty case on a british forum where a guy had his 1" home made sump split in the seam. User name was xdave.

Funny that you mention xdave

In my dozens and dozens of hours of research, I keep coming back to his absolutely HUGE reef drop off tank. I was up until 1am last night re-reading his build thread (about the 10th time I've read it). I didn't know that his sump split, but that's another story as that is just acrylic welded to acrylic.

The main story is that he has a tank made from aluminium profile, plywood covered, acrylic in the viewing panels. He explains it step by step and his tank has been going for a few years now.

His tank is something silly like 1200 gallons, 30mm acrylic, 30mm marine plywood, but pretty standard 45mm square aluminium profile. I could essentially copy one half of his tank (i.e. only one drop) out of the same materials.

Tried. Tested. Waterproof.

 

[JDL121]

I have some DIY plans formulating and currently in the stage of deciding whether to use glass or acrylic after receiving quotes for both.

I'll share the plans later of course and I think you'll love them!

But first... my question... how do you attach an acrylic 25mm sheet to a plywood aquarium?

I've trawled the internet and can't find a good answer. Lots of talk about using the wrong sealants and leaks occurring, which of course I want to avoid, but nothing definitive or clear or put in the form of a simple picture.

I'm okay with the glass option... just correct aquarium sealant and a wooden beam frame to sit the glass within.

Thanks all
Scott

I saw a post on you tube where they did this by having pre drilled holes every 6 inches or so and literally bolting the acrylic to the ply and then glass fibre all around the joint... I am very keen on trying this option as the weight difference is so good... as for the opinion that acrylic bows is a myth in my experience... I had an acrylic aquarium specially made which was 60" x 24" x 24" and only 12mm thick it never showed any size of stress and that was set up for 10 years plus !!