At what point is acrylic 'better' than glass?

[Lowell Lemon]

Lowell.. what part of WA state are you in? I thought for a second you were James from Envision.
FWIW, here is a picture of my DIY 600 acrylic build. James told me to go 1" for Zero deflection on the 30" tall panels and of course, he was right. Machining 1" thick acrylic is NOT fun. The tank was not full of water at the time. You can't see the waterline now. With the lights off, the tank looks AMAZING.

Eastern Washington on the Idaho border. James does amazing work. I sold tanks through the local stores in Portland years ago like Upscales Fish and Reptile, Soutas Saltwater to name a few. I know Travis is still running Upscales but not sure about Rick at Soutas. I had customers in 5 states and out of the country. We built commodity tanks right on the thin side to compete with Sea Clear, Clarity Plus and others. When it came to customs we always built much heavier more like James. Built every one of them up to 2" thick materials at 16' long. So much fun but not the best business model! Love the aquarium industry and made lots of good friends over the years.

 

[pdxmonkeyboy]

Nice.. i know that it was you that spilled the beans about the "special sauce" formulation for welding acrylic. When I picked up my sheet goods the guy mentioned james and I asked if I could call and pick his brain.

They keep 1" acrylic in stock just for him. Anyways, i ended up going out to his shop and buying some of his solvent. Super nice guy, REALLY nice shop. Dude has like a 16' long radial arm saw. Pretty idylic really, nice house and huge shop on the mountains of Oregon. He said he is mostly making jellyfish tanks now.

Always nice to meet solid people.

 

[DJKNOX]

Actually, i suggest you do YOUR research. The refractive index of acrylic is much closer to water than glass is. This is one of the reasons you cant tell how thick the acrylic is when viewing water throught it.

If glass is so strong... why are deep water submersible sub windows and windows on space craft made of acrylic? You cant cherry pick data to support your assumptions.

I believe I explained this in my summary. The benefit of acrylic is that it can be manufactured at thicknesses beyond what is practical for glass. But submersible windows are not what is under debate here... which are aquariums in the 3 to 4 ft deep range. Of course panel strength is a function of the material AND the thickness. You are making valid points that are not specifically relevant to this debate as we are not building a submersible. Note that submersible windows are typically very small diameter BECAUSE acrylic's flexibility and high deflection is not suitable for anything but a small viewing window. Because a technology is used for a space craft doesn't mean it is economical for a Cessna.
Concerning refractive indexes, yes acrylic is closer to water but again that is different than "clarity." I don't have any issues with how glass aquariums look, but if one prefers the acrylic look, that's another point in the acrylic pro column. No argument there - just not a factor for me personally.

As for cherry picking, I'm afraid it is you who are choosing to ignore very key factors: acrylic is very soft vs glass and therefore sctaches easily; AND it is very expensive, especially at 150 to 200% thickness.

 

[DJKNOX]

It does appear that at this point you are trolling. Best of luck. This behavior should not be encouraged on forums. I'm out.

Ah... a few people have formed an opinion and don't like the topic being fully explored. This is not trolling, this is technical examination of an assertion. You all seem to think that I am arguing against acrylic. I am not necessarily doing so. I'm shedding light on all factors and thus far my conclusion is that glass is a viable option up to, but not exceeding, this size range. Sorry to rain on the "acrylic is perfect parade!" And I find it incredulous that folks who attack me for sharing valid technical explanations believe I'm the troll. But it seems to me that some on this thread don't want a robust debate but rather just affirmations of previous purchase decisions.

 

[DJKNOX]

I know this has been debated to death by now.

Just a few observations. A man convinced against his will is of the same opinion still. Not sure who said that originally but it seems to bear weight in this discussion.

Of all the large acrylic failures mentioned only one resulted in death and injury and the core reason is substandard Chinese acrylic panels. Unless you have experience with various cell cast acrylic you have no idea the difference in quality and process. There are two types of acrylic cross linked and linear and I am sure the tanks that failed in Disney World were cross linked and maybe a couple of the others as well. You see when you get into public aquarium size displays there are only a few players world wide and I know some of their work and reputations. Unless you know the difference you can not appreciate the difference in risk during the bonding phase. The other aquariums allowed time to save the majority of the livestock and no one was injured. A glass panel would explode and you would be riding a wave right out the nearest opening. If the panel was not tempered you would be cut by large shards of glass. Know a guy that builds submarines and there is no glass in any viewing panels...wonder why?

Before you build just try to get an insurance company to underwrite a policy for your glass aquarium. Compare the cost of that insurance and you will discover why cell cast acrylic is the choice of public aquariums world wide.

You never owned an acrylic tank but you are an expert and authority on both glass and acrylic?

As a manufacturer of acrylic tanks my insurance was $750.00 a year for $2 million aggregate. I could not find an insurance company to underwrite my purchase of an existing glass tank manufacturer that was for sale at the time. This was 1988 for a dollar comparison. Insurance companies must know something about risk would you agree?

Thanks Lowell for that insight. Sometimes the enemy we can see is better than the enemy we can't. Thus at least I know what I am getting with silicone seals. The acrylic bonding scares me as much as imagining a glass panel with a 5 safety factor does. And please note that I never claimed to be a materials expert, nor an aquarium design expert. But I do understand structural engineering and know there are trade-offs. If you are an expert, please share what assumptions about the two materials that I may have misrepresented?

Concerning submersibles, as I stated in an earlier post, that is not an argument as to why glass can't be used at 3 or 4 feet water depth.

Concerning insurance companies, actually I contacted my insurer of 35 years and they gave me the green light for adding this to my water damage coverage, 3rd party liability and contents insurance - regardless of glass or acrylic provided suitable safety factors are deployed in the design. My home design contains a containment basis around the aquarium in case of a significant leak while I'm absent.

Seeing you are experienced in acrylic tank construction, can you share insights as to what supplier/manufacturer of 1.5" acrylic is best suited?

 

[DJKNOX]

I’m not trying to get in the debat I just wanted to let you know I own a 20 year old acrylic 300 gallon tank. The Dimensions are 96x24x28 and 1/2 inch thick. So I want to tell you after 20 years of use this tank is as clear as it was on day 1. No yellowing at all. Tank is cloudy on inside a little from normal cleaning a wear. Just needs some buffing and will be crystal clear. Tell me what glass tank would have seals that are not leaking after 20 years? 20 years !!!!! My only beef is the obvious a 300 gal with 1/2 acrylic has the whole top braced so only has little holes on top for access and due to the 1/2 acrylic I can see slight outward bow in front panel no one would notice except me. 20 years ago this is how they was being built. So anyways I’m in process of restarting that system after complete tear down to clean and buff inside of tank. Just thought I’d throw this out there to confuse you more

Fordtech that feedback is appreciated - especially on the no-yellowing as claimed by others here. 1/2" acrylic is under-designed and so requires excessive bracing. So you actually help make my point that a well-designed acrylic tank really should use a much heavier wall than one would with glass. But once that heavier wall is used with good bracing, I think the acrylic design is structurally sound. As for 20 year silicone seals, I know several folks still running their tanks from the 1990s and have never replaced the structural component of their joints. They have re-lined the inner-seal portions. Those tanks are 125 to 400 gal in size but none are deeper than 27."

 

[kangadrew]

@DJK who have you hired to build this tank? I can pretty much guarantee that nobody in the industry is going to build you a solid glass tank at those dimensions.

Drew

 

[Matt1997]

When you get a split seam on a glass tank. Acrylic becomes better

 

[Lowell Lemon]

In my experience Polycast by Polyone is the best product in the thicker acrylic range in the United States. Mitsubishi also is a solid choice for large acrylic panels but much harder to get. I have built a few large tanks but did not claim to be an expert. I have just relayed my experience with both glass and acrylic and have built small tanks only with glass.

I did build (2) 16'×3'×4' acrylic tanks for a customer that was seamed end to end right in the middle cause the customer did not want to wait three years for the custom panels to be cast. I think we placed them into service in 1993 and to my knowledge they are still I service today.
Getting close to 20 years in service for a large display. 2" thick acrylic with 1.5' tops and bottoms all seamed in the middle of the span. 3/32" deflection in the center (left to right and top to bottom after) 30 days static load test before delivery.

I am professional in my approach and thorough, but not an engineer. I do use the engineers that work for the acrylic companies to spec material for large builds.

Cessna uses acrylic windshields also...just to be clear lol. Never seen glass in a modern aircraft or military aircraft but I digress.

 

[pdxmonkeyboy]

Well, @Lowell Lemon I think polycast is garbage. Sorry, just trying to keep the thread alive.

I used plexiglas G from arkema for all the viewing panels. They also had some arkema plexiglas that they referred to as "plex-mex. Made in mexico out of the same stuff but it in open casting product. It was 30% cheaper but he said you may take the masking off and find a fly or something encased in the acrylic. Which I thought was pretty funny. I used it for top and bottom but the sheets looked great.

Anyways, still not as strong as glass. LOL

 

[DJKNOX]

In my experience Polycast by Polyone is the best product in the thicker acrylic range in the United States. Mitsubishi also is a solid choice for large acrylic panels but much harder to get. I have built a few large tanks but did not claim to be an expert. I have just relayed my experience with both glass and acrylic and have built small tanks only with glass.

I did build (2) 16'×3'×4' acrylic tanks for a customer that was seamed end to end right in the middle cause the customer did not want to wait three years for the custom panels to be cast. I think we placed them into service in 1993 and to my knowledge they are still I service today.
Getting close to 20 years in service for a large display. 2" thick acrylic with 1.5' tops and bottoms all seamed in the middle of the span. 3/32" deflection in the center (left to right and top to bottom after) 30 days static load test before delivery.

I am professional in my approach and thorough, but not an engineer. I do use the engineers that work for the acrylic companies to spec material for large builds.

Cessna uses acrylic windshields also...just to be clear lol. Never seen glass in a modern aircraft or military aircraft but I digress.
[/QUOTE}
thanks for the feedback

 

[DJKNOX]

When you get a split seam on a glass tank. Acrylic becomes better

Yeah I can only imagine. But do properly designed and constructed glass aquariums really just have a seam split? A poorly bonded acrylic seam produces the same result - its all about the product's design and quality control isn't it?

 

[Shep]

Stop attacking each other, stop name calling and stay on topic please! Would hate to have to thread ban people

 

[Lowell Lemon]

@DJKNOX
If I understand your dimensions correctly your glass tank will be 10'×6'×4' (LxWxH) correct? If that is correct for a 3.8 to one safety factor you need 1.3937" thick side panels and a 1.69685" thick bottom glass panel. This is from a glass calculator on line for aquariums. Knowing that both glass and acrylic are not dimensional stable then one would assume you need panels at least 1.5 " thick and 1.75" for the bottom. Where would you get this material and would you build the tank on a pad first and then build the house around it? Just curious cause the materials you talked about seem on the thin side to be generous. Your deflection on the main panel will be at least .55mm which is rounded to .022". Your bottom panel allows for .46mm or .018" deflection. Sounds like an engineering challenge just for the pad flatness alone!

I can't imagine shipping a complete tank in glass in these dimensions without mission capable material handling on both ends of transport. Flat bed truck would make the transport much easier. I estimate your tank weighing about 3900 lbs dry before crates. The heavy panel is the bottom at 1365lbs. Face panels at 780lbs each, end panels at 450 each. I have the equipment to handle the glass if you want to build on site.

Sounds like a fun project!

 

[DJKNOX]

@DJKNOX
If I understand your dimensions correctly your glass tank will be 10'×6'×4' (LxWxH) correct? If that is correct for a 3.8 to one safety factor you need 1.3937" thick side panels and a 1.69685" thick bottom glass panel. This is from a glass calculator on line for aquariums. Knowing that both glass and acrylic are not dimensional stable then one would assume you need panels at least 1.5 " thick and 1.75" for the bottom. Where would you get this material and would you build the tank on a pad first and then build the house around it? Just curious cause the materials you talked about seem on the thin side to be generous. Your deflection on the main panel will be at least .55mm which is rounded to .022". Your bottom panel allows for .46mm or .018" deflection. Sounds like an engineering challenge just for the pad flatness alone!

I can't imagine shipping a complete tank in glass in these dimensions without mission capable material handling on both ends of transport. Flat bed truck would make the transport much easier. I estimate your tank weighing about 3900 lbs dry before crates. The heavy panel is the bottom at 1365lbs. Face panels at 780lbs each, end panels at 450 each. I have the equipment to handle the glass if you want to build on site.

Sounds like a fun project!

Thanks Lowell. I plan to use double euro bracing and cross bracing, and so the prelim. front panel calcs for glass are a little different from yours. Also the water level will actually be 42" so that makes a difference too. As for the bottom panel, a super stiff stand has been designed with a lot of cross supports, so I don't quite need that heavy bottom as the spans for deflection are quite manageable. Instead, I do plan to use "euro bracing" around the bottom perimeter to effectively double the thickness of the bottom panel joints to the front and sides. I was very much hoping to source 1" glass but that is proving difficult.

Anyway, the design is still preliminary and yes this is an engineering challenge from many angles. The living room is being specially designed to support this tank while the fish room will be in the basement below. I actually would like to use acrylic but really hate the scratching and buffing - am now investigating whether harder acrylic can be purchased. And the acrylic welding scares me just as much as silcone seems to scare some folks here. Whether the tank is pre-assembled and delivered or assembled on site is still to be determined. I believe it is possible to deliver but am leaning towards site assembly provided I can arrange that economically.

I'm still in the planning stage of the house and so this build is still a ways off. I'll follow up with you once I've decided on exactly what I want.

 

[pdxmonkeyboy]

The only thing i can try to convince you is that a reputable acrylic builders seams are NOT going to fail. There is literally no chance. The solvents they are using are extremely aggressive and they have the knowledge to custom mix solvents to deal with the additional thickness. I would imagine they would slow it down a little. You can also literally look at the seam and know how good it is.

There ARE types of acrylic that are more scratch resistant but builders will not use them because they dont bond well. Ask me about my high density import acrylic tank that I built with weld-on.

James at envision acrylics wouldn't skip a best if you ordered a tank that large.

I worked in a glass factory for a summer in Ohio. You can absolutely get 1" and 1.5" glass, it came on 10 x 20 foot sheets and then we would cut them to make glass doors and what not. But yeah.. the cost to cut and ship panels of that size around...YIKES!

Anyways. I think we have suffciently beat this to death, resuscitated it, and beat it to death again.

 

[DJKNOX]

The only thing i can try to convince you is that a reputable acrylic builders seams are NOT going to fail. There is literally no chance. The solvents they are using are extremely aggressive and they have the knowledge to custom mix solvents to deal with the additional thickness. I would imagine they would slow it down a little. You can also literally look at the seam and know how good it is.

There ARE types of acrylic that are more scratch resistant but builders will not use them because they dont bond well. Ask me about my high density import acrylic tank that I built with weld-on.

James at envision acrylics wouldn't skip a best if you ordered a tank that large.

I worked in a glass factory for a summer in Ohio. You can absolutely get 1" and 1.5" glass, it came on 10 x 20 foot sheets and then we would cut them to make glass doors and what not. But yeah.. the cost to cut and ship panels of that size around...YIKES!

Anyways. I think we have sufficiently beat this to death, resuscitated it, and beat it to death again.

That's kinda what I feared - harder acrylic doesn't bond well. I should have mentioned that I want low iron glass - and it seems it is not produced thicker than 3/4" in the US. If anyone knows where to source 1" low iron glass in the US, I will be very grateful for a heads up. ELOS mentioned that they can use 22mm sapphire/diamond glass - so I will pursue an option with them.

And I should not that at the very least, the acrylic needs to be 75% thicker, and really 100% thicker if one wants the same bracing configurations to produce very similar deflections. Therefore, an acrylic tank is not really much lighter. Half the weight but 75% to double the thickness. I do concede that acrylic is more durable and so shipping heavy acrylic panels or tanks doesn't pose the same risk as shipping heavy glass panels or tanks.

Would you agree that if glass, then on-site assembly seems the wiser route... but if acrylic, pre-assembly in the shop and shipment might be safer?

 

[pdxmonkeyboy]

I highly doubt that anyone will ship a glass tank that big. In fact, I am quite certain of it.

On the other side of the equation, nobody is going to assemble an acrylic tank on-site. There is a fair amount of machining work to be done post assembly.

I hope you have a big chunk of change set aside, this is going to easily be in the 40-50k range to be fully set up and running.

 

[kangadrew]

@DJKNOX I searched Google for "1 inch low iron glass" and the third result is a company that carries 1" Starfire in the US.

1 inch Thick Glass - American Glass Top

Learn more about our one inch (1”) thick glass available in regular glass or Ultra Clear Starphire Glass. Read about sizes, specs, and availability.

www.americanglasstop.com

Update if you search "25mm starfire glass" it gives you a ton of companies that carry it, or claim to anyways

 

[Lowell Lemon]

@DJKNOX I searched Google for "1 inch low iron glass" and the third result is a company that carries 1" Starfire in the US.

1 inch Thick Glass - American Glass Top

Learn more about our one inch (1”) thick glass available in regular glass or Ultra Clear Starphire Glass. Read about sizes, specs, and availability.

www.americanglasstop.com

Update if you search "25mm starfire glass" it gives you a ton of companies that carry it, or claim to anyways

Limited to 110" so 10" short of the dream.