Building a 75g all glass tank

[Anti-Pjerrot]

wow - nice work.

Im planning to do a polycarbonate tank soon, 2,1gal nano so not much work there - but the tips u got a great. Thanks.

[scolley]

Originally Posted by Anti-Pjerrot

wow - nice work.

Im planning to do a polycarbonate tank soon, 2,1gal nano so not much work there - but the tips u got a great. Thanks.

Thanks. For anyone thinking about something similar... it's all in the masking! Invest the hours of painstaking masking work, and you'll get years of a great looking tank in return.

Good luck with the polycarbonate! I hope we will see some details on that.

[Anti-Pjerrot]

it's all in the masking!

Thats possibly the best advice I can ever get.

[Hoppy]

How do you glue polycarbonate? Does it use a solvent glue so it welds the seams, or a stickum adhesive like silicone?

[csf]

I made a 10" cube poly tank. You use a solvent welder. You basically build the tank with lots and lots of tape (masking and electrical) to hold things together and tokeep the sides clean and then you run a bead around all of the internal corners.

At that point the solvent "spreads" to weld the entire seam. But once it gets "wet" don't move it. Check garf (.org I think). They have a tank builder helper for both glass and acrylic tanks. I also didn't use their framing pieces and have had no issues w/ bowing (but it's only a 10" tank).

[Hoppy]

Acrylic is cemented with solvent, and it actually welds the material together, but I don't know if polycarbonate, a different plastic, is welded the same way. That's why I asked. I've never seen anything about cementing polycarbonate.

[wendle]

hi scolley, your tank came up really nice, but i have to say you did quite a few things to make it a lot harder for yourself than it needed to be

i have built a lot of big aquariums and done a lot of commercial glazing and showcase work, so i would like to offer a few tip to the people reading this. but i don't want to critisize your work as your end product turned out great.

the first thing i noticed is that you put the bottom of the tank on the bottom, under the front/back and ends. the easiest way to build the tank is to put the bottom inside the front, back and ends. that way you can lay out all your panes, run the silicon onto the face of the joint surfaces, and then just stand them up.
also, you aren't doing yourself any favours by clamping the whole thing up tight. the strongest way to produce a silcon seam is to have a 1 to1.5mm gap between the glass surfaces, the gives the join flexibility without having to worry about tearing a thin membrane of silicone away from the glass.
i lay the panes out, apply the bead of silicon to the joint surfaces, stand up one end and one face and push them together with hand pressure (big tanks take two or three people to stand these first two panes up) then stand up the other end and the last face, just squeeze the whole lot lightly together with hand pressure, making there is no less than 1mm of silicon seam at the visible joints. obviously you can't see the seams along the bottom, but if your cutting is accurate, this won't be a problem. i then wet my finger and run it around the bottom joints only to smooth in the squeeze-out. then walk away from the tank and don't touch it for a week. the vertical seems don't need to have the squeeze-out flattened out. it can just be sliced off with a razor blade when it has cured.

i don't mask ANYTHING up, and this is why: assembling the tank as per above means you shouldn't have any excess silicon anywhere, the time between applying the silicon and walking away from the tank is only a couple of minutes. the only time you should get any silicon on your hands if when you run your finger around the bottom, and as soon as you do that you should be walking away from the tank and forgetting about it.

for a tank with lids and braces across the top, i just glue a long rib to the front and back of the tank a day before i assemble the tank. after the tank has cured for a couple days i will then glue the braces across it.

a flat surface is very important for assembly, there is no problem with doing it on the ground with this method as you'll only be kneeling down for a few minutes and then it will be all over, but it has to be flat. thick formwork ply or thick MDF/chipboard work well, as long as they are nice, new, flat sheets.
i put newspaper down under the bottom so the tank doesn't end up glued to the work surface, you can then just cut the paper away when the glue has dried.

cliff notes: fit the base inside the faces, no clamps, no messy fingers/tools, no worries!

[scolley]

Hey Wendle, where the h*ll were you when I needed you!!!! It's a little late for all the good advice now!

Just kidding.

I'm thrilled to have you post here. Thanks!


The whole point of my putting anything up at all is to spread the knowledge. If you can top mine, by all means please do! Better for everyone!

I'm not sure why I assembled the bottom across all the panes. There was some process of evaluation based on internet available information, and that was my conclusion. But I can certainly see a great benefit in what you are suggesting. Not the least of which having to buy fewer tools, and just being easier. The way I did it was a PITA.

I'm curious about the trimming... do you mean that you just trim the inside seams flush with the edge, so there really is no seam, other that what is between the glass?

Also, what size tanks have you constructed like this? And can you offer additional insight into appropriate thicknesses?

Thanks a mil' for posting Wendle. Can't wait to hear more!

[wendle]

Originally Posted by scolley

Hey Wendle, where the h*ll were you when I needed you!!!! It's a little late for all the good advice now!

Just kidding.

I'm thrilled to have you post here. Thanks!


The whole point of my putting anything up at all is to spread the knowledge. If you can top mine, by all means please do! Better for everyone!

I'm not sure why I assembled the bottom across all the panes. There was some process of evaluation based on internet available information, and that was my conclusion. But I can certainly see a great benefit in what you are suggesting. Not the least of which having to buy fewer tools, and just being easier. The way I did it was a PITA.

I'm curious about the trimming... do you mean that you just trim the inside seams flush with the edge, so there really is no seam, other that what is between the glass?

Also, what size tanks have you constructed like this? And can you offer additional insight into appropriate thicknesses?

Thanks a mil' for posting Wendle. Can't wait to hear more!

putting the base inside just makes things sooo much paster and neater, especially when building a lot of small tanks at once, back in the day i would build 20 or 30 (!) standard 2ft or 3ft tanks for pet shops all in one hit. you have to be fast, tidy and organised to pull that off i would hate to have to try it with the bases sitting under the faces, pretty frustrating. the way i do it there is no need to clamp anything. occasionally if i am building a very large tank with no-one to help, i'll tape the first corner together to stop things moving around. once the whole thing is together, the suction produced by the seams will never, ever, let a pane move.

as far as trimming the vertical seams, on tanks built from 10mm (3/8") or thicker, i cut all the excess off. i use dow corning V2 sealant, which also comes in black whick looks really nice sometimes on tanks made from 15mm or 18mm glass. i must say though on small tanks made from thin 4mm or 5mm glass i am not confident with leaving the corners frameless and exposed as one small knock can shell the glass and crack the tank, so on those i use a small plastic angle on the outside and flatten the squeezeout on the inside same as i always do for the bottom seam.

biggest tank i have built was 8" x 3" x 4" (high) it was a beautiful tank in 18mm glass fitted into some really nice joinery..

as far as thickness, for tanks with braces across the top, i work on 10mm for 700mm high, 12mm for 900mm high, 15mm for 1000mm high, and 18mm for anyhting over that. anything without braces on the top, like yours, really needs special consideration and goes up at least one glass thickness.

[Hoppy]

One thing that deterred me from trying to build a tank was the difficulty in getting pieces of glass cut as accurately as I felt would be needed. Do you cut your own pieces, or buy them from a place that is able to precision cut them for you? Does the one mm gap for silicone give you a bigger tolerance on the cut sizes?

[scolley]

Originally Posted by Hoppy

Does the one mm gap for silicone give you a bigger tolerance on the cut sizes?

I had to accommodate for silicone gaps, as you can see in these pics I gave to the glass cutters.







But if you are doing it Wendle's way, I would think that would be unnecessary.

Originally Posted by wendle

as far as thickness, for tanks with braces across the top, i work on 10mm for 700mm high, 12mm for 900mm high, 15mm for 1000mm high, and 18mm for anything over that. anything without braces on the top, like yours, really needs special consideration and goes up at least one glass thickness.

Thanks! That's great practical advice for sizing. And consistent with my findings... width matters a bit, but at the end of the day, your thickness decisions are really driven by the tank height.

Also thanks for the tip on the Dow Corning V2 sealant! Gotta see if they make that in the states.

Wow! Now I want to try this out on another tank! Could be a lot easier this time...

[wendle]

that's another advantage of putting the base inside the faces, you cut one long split for the tank depth and dock it to length for the base and ends, makes accuracy a lot easier.
cheapest/easiest way to deal with glass is to buy "splits" off a wholesaler. they are basically long rips off a full sheet, the width of which should be one of the dimensions you need, so you are only cutting in one axis for most of your parts.
hope that makes sense?

if you are going to be cutting a lot of glass, get yourself a speed cutter like this one: (hope pic works)

[wendle]

one other thing i forgot to mention.
when you are applying your silicone to the faces of the glass, don't drag the nozzle along the glass. cut the nozzle so the goop comes out at the same thickness as the glass, then hold the nozzle about an inch off the surface and keep moving at the right speed so the silicone hangs down and keeps laying onto the glass in a nice consistent worm. dragging the nozzle along the surface always leaves air bubbles in the glueline (which look terrible if you are building a bare-glass tank) and can't be good for strength.
the nozzles are also made from a nylon that silicon doesn't stick to (for obvious reasons) so you don't want any residue of that particular plastic abrading onto the glass from dragging the nozzle along.
this is probably the part of building aquaria that takes the most practice.

[scolley]

Originally Posted by wendle

when you are applying your silicone to the faces of the glass, don't drag the nozzle along the glass. cut the nozzle so the goop comes out at the same thickness as the glass, then hold the nozzle about an inch off the surface and keep moving at the right speed so the silicone hangs down and keeps laying onto the glass in a nice consistent worm. dragging the nozzle along the surface always leaves air bubbles in the glueline.

Thanks Wendle! Those bubbles gave me fits! That's the reason why I recommended using so much silicone because the only time I didn't have bubbles way when I was using tons of it.

But in retrospect I'll wager it was exactly as you are suggesting here... it's not that I was laying down more silicone per se, but that I was laying a bead at least the width of the thickness of the glass! Which when compressed, of course extrudes a lot of excess silicone.

Not dragging the tip is some great insight too.

Thanks!

[Hoppy]

How do you handle the weight of a large tank like this? Just the thought of trying to move it without breaking it while gluing it together, cleaning up the excess glue, cleaning the outside, etc. just scares me.