My idea for a DIY plywood aquarium

[Big Fish Freak]

Personally I would avoid tempered. You see tanks all the time that crack. If that was ever a tempered piece it would be all she wrote. Also static load does weird things to tempered... with pressure put on it just the slightest anything sometimes make them explode.

So is there another way to strengthen glass without making it tempered? I have heard of people getting low iron glass but if I remember correctly that was for extra clarity of the glass..Going non tempered will certainly drive down the cost, I just want to make sure that if the fish decided to lunge at a piece of food that was in front of the glass and accidentally bump into it that it isn't gonna break..

 

[spiff44]

Just getting it thicker is the only way I know. There are plenty of safety calculators that can show the thickness you'll need.

I guess you have to weigh the pros and cons of the tempered.. yeah, its a lot more strong initially, but if if breaks its a catastrophic break every time. As far as I know, you can't even chip tempered... if you do its a time bomb. Windshield are the only exception to this because they're layers of glass and adhesives designed specifically to stay intact. There are dozens of tanks on this site where the plate glass cracked and they were able to at least deal with the it.. drain it while its leaking, then patch it after the fact or replace the glass. Versus an instantaneous wall of water gushing into the room.

 

[Drstrangelove]

So is there another way to strengthen glass without making it tempered? I have heard of people getting low iron glass but if I remember correctly that was for extra clarity of the glass..Going non tempered will certainly drive down the cost, I just want to make sure that if the fish decided to lunge at a piece of food that was in front of the glass and accidentally bump into it that it isn't gonna break..

Glass can be altered after it's made to become stronger (thermal is a common method) as that induces physical changes in the material. The properties of the glass change. (This is done at the glass factory I'd imagine.) I don't recall iron content having any effect on the strength of the glass. There is a type of glass in between tempered and plate, but I don't recall people using it.

Glass cracks are often caused by adequate deflection, although animals/rocks/baseballs/toys/fists, etc hitting the glass can have the same localized effect. Deflection therefore needs to be avoided as unlike wood which can deflect well and return to form, glass can only deflect a relatively small amount before it fails.

In every case you have choices. Stronger/thicker glass has lower deflection therefore is less prone to crack regardless of the cause. Tempered/hardened glass is more expensive of course, but then again thicker plate glass is expensive. My assumption is that the trade-off----when safety is not an issue----typically favors plate glass since tempered glass is not a common glass type. It's used for safety reasons in cars, front doors, sliding glass doors, cookware, etc not for cost cutting reasons but because it's much safer.

If you "happen" to get a good price for tempered glass, it might be cost effective, but under normal circumstances people don't get better costs by using tempered. In other words, it's cheaper to get thicker plate glass. A well sized piece of plate glass (using a safety factor of let's say 3.8) will normally give all the strength needed. Thinner pieces (safety factors down to 2.5) are sometimes used but will of course be more prone to crack if not properly supported or if subject to a sudden stress (e.g, an animal or baseball hitting the glass.) At 2.5, other issues come in to play (is the glass of good quality, has the glass had unusual temperature fluctuations over time, has the glass had collisions, etc. all of which might imply microscopic fractures in the glass.)

Euro builds are an example of thinner glass used with much more support than "typical" builds. There are also builds with no support but with much thicker glass. So there are trade-offs.

If one has large, active animals prone to hit the glass, I'd think that a build using a 3.8 safety factor with strong support would handle almost anything reasonable. It might be overkill, but iirc, tanks are rarely built stronger than that using glass.

 

[coolkeith]

The stand is going on a flat concrete slab in my garage..this whole tank is planned out to be easy, so I am not worried about having to work under it..I am looking forward to getting in the tank to clean it or move stuff around in it

The cinder block stand isn't too much of a bad idea. Would I just structure it like I would a wooden stand? That makes the cost about 1/3 of a wooden stand based on the same design I have for my stand. Would I bond the blocks together with mortar or just stack em? Stacking them would make the stand very portable. And would I lay them on the 8" side with the holes horizontal or on the 6" side with the holes vertical?

Cinder blocks are normally 16" × 8" × 8" and stacked with the holes facing up. Limitless options with how you layout the blocks.

 

[Big Fish Freak]

Glass can be altered after it's made to become stronger (thermal is a common method) as that induces physical changes in the material. The properties of the glass change. (This is done at the glass factory I'd imagine.) I don't recall iron content having any effect on the strength of the glass. There is a type of glass in between tempered and plate, but I don't recall people using it.

Glass cracks are often caused by adequate deflection, although animals/rocks/baseballs/toys/fists, etc hitting the glass can have the same localized effect. Deflection therefore needs to be avoided as unlike wood which can deflect well and return to form, glass can only deflect a relatively small amount before it fails.

In every case you have choices. Stronger/thicker glass has lower deflection therefore is less prone to crack regardless of the cause. Tempered/hardened glass is more expensive of course, but then again thicker plate glass is expensive. My assumption is that the trade-off----when safety is not an issue----typically favors plate glass since tempered glass is not a common glass type. It's used for safety reasons in cars, front doors, sliding glass doors, cookware, etc not for cost cutting reasons but because it's much safer.

If you "happen" to get a good price for tempered glass, it might be cost effective, but under normal circumstances people don't get better costs by using tempered. In other words, it's cheaper to get thicker plate glass. A well sized piece of plate glass (using a safety factor of let's say 3.8) will normally give all the strength needed. Thinner pieces (safety factors down to 2.5) are sometimes used but will of course be more prone to crack if not properly supported or if subject to a sudden stress (e.g, an animal or baseball hitting the glass.) At 2.5, other issues come in to play (is the glass of good quality, has the glass had unusual temperature fluctuations over time, has the glass had collisions, etc. all of which might imply microscopic fractures in the glass.)

Euro builds are an example of thinner glass used with much more support than "typical" builds. There are also builds with no support but with much thicker glass. So there are trade-offs.

If one has large, active animals prone to hit the glass, I'd think that a build using a 3.8 safety factor with strong support would handle almost anything reasonable. It might be overkill, but iirc, tanks are rarely built stronger than that using glass.

So what are the advantages of thermal treated glass, and/or would it be beneficial to use thermal treated glass?
I'm still learning about safety factors with glass, so be easy on me...
Are you saying that a saftey factor of 2.5 is not good enough? Because every calculator I have used says 2.5 is safe for the size I am using (unless I am using the calculator wrong) at 19mm or 3/4" glass I'm so lost right now..lol

 

[Big Fish Freak]

Cinder blocks are normally 16" × 8" × 8" and stacked with the holes facing up. Limitless options with how you layout the blocks.

Awesome..I can't wait to get started..You just saved me easily over $100. Should I just stack them or would gluing them together be best? I have heard a lot of people saying not to stack them more than 3 high. Is this a stability thing? Or is that just someone being overly cautious? I built a pond out of cinder blocks with my father in law last summer, but we put rebar crossbeams and filled the holes with cement so I know that thing is solid..this is a bit different of a build, so I am not sure of how different it will be..

 

[coolkeith]

Awesome..I can't wait to get started..You just saved me easily over $100. Should I just stack them or would gluing them together be best? I have heard a lot of people saying not to stack them more than 3 high. Is this a stability thing? Or is that just someone being overly cautious? I built a pond out of cinder blocks with my father in law last summer, but we put rebar crossbeams and filled the holes with cement so I know that thing is solid..this is a bit different of a build, so I am not sure of how different it will be..

You can dry stack a single row of them, if you only go 2 or 3 high. You can go higher with a double wide stack or if you use a surface bonding cement. The stability depends on the design. If you stack them like they do on a pallet, that would be as sturdy as you can get.

Perhaps you should build another cinder block pond with the father in law since you already know how to do that. Just put a window in it this time.

 

[Big Fish Freak]

You can dry stack a single row of them, if you only go 2 or 3 high. You can go higher with a double wide stack or if you use a surface bonding cement. The stability depends on the design. If you stack them like they do on a pallet, that would be as sturdy as you can get.

Perhaps you should build another cinder block pond with the father in law since you already know how to do that. Just put a window in it this time.

I would totally build another block pond but the goal is to do something different...we did put a window in that pond...they went with a plastic liner which IMO I would not have done. It is just not the look I want. And I think that with how poreous cinderblocks can be sealing them seems like it would take a lot of material..and windows would be fun to try and seal to them..I may build a small one to try out, and maybe I will just go with a block tank for the big one?? But for now, I stick to my original plan.

I will play around with designs, but for right now I think I will go with the pallet style stacking for the four corners, and the will do 2 single wide columns on each short side, and do probably 3 single wide columns across the back, 2 across the front for sump access, and I will throw more single wide stacks to support the inside middle of the bottom so it doesnt fall out from under itself..I think that should be pretty solid.
I will probably top it with a sheet of plywood and probably foam to make up for any unevenness..


Next is plumbing and what I'm gonna do for a sump..

 

[Drstrangelove]

So what are the advantages of thermal treated glass, and/or would it be beneficial to use thermal treated glass?

Safety is it's main advantage. It's stronger as well, but much more expensive.

I'm still learning about safety factors with glass, so be easy on me...
Are you saying that a safety factor of 2.5 is not good enough? Because every calculator I have used says 2.5 is safe for the size I am using (unless I am using the calculator wrong) at 19mm or 3/4" glass I'm so lost right now..lol

I would phrase it differently. When I grew up, we didn't have seat belts, shoulder harnesses, or air bags, yet we felt relatively safe. We were relatively safe. But many people felt it wasn't safe enough. It wasn't a white and black question, it was a relative one.

A tank with a 2.5 safety factor might be safe, but it isn't going to be as safe, all other things being equal, as a tank with a 3.8 safety factor. I think you can find people who have built tanks with 2.5 safety factors (in this forum perhaps) and those tanks are fine. However, there is a real and measurable difference between a 2.5 and a 3.8 safety factor. E.g., the amount of deflection the glass has will differ. The lower you go, the more likely you are to see a failure.

"Buildings commonly use a factor of safety of 2.0 for each structural member. The value for buildings is relatively low because the loads are well understood and most structures are redundant. Pressure vessels use 3.5 to 4.0, automobiles use 3.0, and aircraft and spacecraft use 1.2 to 3.0 depending on the application and materials. Ductile, metallic materials tend to use the lower value while brittle materials use the higher values." https://en.wikipedia.org/wiki/Factor_of_safety

Glass is a brittle material. https://en.wikipedia.org/wiki/Brittleness

 

[Big Fish Freak]

Safety is it's main advantage. It's stronger as well, but much more expensive.

I would phrase it differently. When I grew up, we didn't have seat belts, shoulder harnesses, or air bags, yet we felt relatively safe. We were relatively safe. But many people felt it wasn't safe enough. It wasn't a white and black question, it was a relative one.

A tank with a 2.5 safety factor might be safe, but it isn't going to be as safe, all other things being equal, as a tank with a 3.8 safety factor. I think you can find people who have built tanks with 2.5 safety factors (in this forum perhaps) and those tanks are fine. However, there is a real and measurable difference between a 2.5 and a 3.8 safety factor. E.g., the amount of deflection the glass has will differ. The lower you go, the more likely you are to see a failure.

"Buildings commonly use a factor of safety of 2.0 for each structural member. The value for buildings is relatively low because the loads are well understood and most structures are redundant. Pressure vessels use 3.5 to 4.0, automobiles use 3.0, and aircraft and spacecraft use 1.2 to 3.0 depending on the application and materials. Ductile, metallic materials tend to use the lower value while brittle materials use the higher values." https://en.wikipedia.org/wiki/Factor_of_safety

Glass is a brittle material. https://en.wikipedia.org/wiki/Brittleness

Hearing it that way makes more sense..If your gonna get on a skateboard, wearing a helmet is safe, (2.5) but putting on elbow pads and knee pads is much safer (3.8) Makes much more sense now...so what is stronger for this application, glass or acrylic? I guess what I am asking is if I need 3/4" glass for a 2.5 saftey factor, is 3/4" acrylic a 2.5 or would it be stronger or weaker? I plan on using glass as I don't want to spend the $$ on acrylic for a "test" tank..

I am gonna just go with the 3/4" cause I really don't plan on having this fish in this tank for long, just long enough to get the other tank built..and the fish won't be any more than 3' when I move him out of that tank so I think it will be fine there. After he moves out I plan on putting some rays in there...And unless they are brilliant engineers and figure out that if they tap their stingers on the glass in exactly the right places on the glass at the same time I don't think there's any way they can break that glass..