Waterproofing Bottom of Potential Cylinder Aquarium

[Tetra Studio 60]

Hi all, long time reader first time posting!

I recently found a unique cylindrical glass container that I would love to turn into a small (4 gal or so) neocaridina shrimp tank or even possibly just a plant tank, but it has a piece of metal that it sits in and acts as the bottom of the container (pics attached).


I've been trying to figure out the best way to seal this bottom off to prevent unwanted contact between the metal and water but pond shield is the only option I'm sure would be safe and it's a touch pricier than I was hoping for at the only place I know of. Have any of you found good alternatives for pond shield? Or alternatively do any of you have ideas on how I would best go about putting a sealed bottom on this thing?

Cheers, forgive the ignorance if this is a blindingly stupid idea, it was a $6 whim

 

[jjohnwm]

I'm not sure if it's blindingly stupid, but I know that I would never have been able to resist that thing myself and would want to do the same with it as you want to do.

So...predicated by the caution that I don't have it in hand and can't give it a detailed inspection...here's what I would try:

Take it apart and clean/degrease both the cylinder and the base thoroughly. Run a thick bead of silicone all the way around the inside corner angle of the base and lower the cylinder into place, then immediately run your finger all the way around to create a nice neat concave internal bead. This should adhere the glass to the base permanently, and also create a waterproof seal. Then immediately slather the complete bottom of the new tank with a layer of silicone, and spread it thoroughly so that it covers the entire bottom and also merges with the previously-created bead. Let dry and cure for at least a week or so. That's it!

Done carefully, I believe that this will give you what you want, i.e. a sealed, safe-for-fish cylinder aquarium. Forget about ever picking it up by the upper rim, especially if it has any water in it. I believe this method will preclude any silicone oozing up onto the outer surface of the glass on the exterior, but it that happens, just remove it carefully with a razor blade once it cures. Silicone being forced up into the contact surface between the glass and the vertical lip would be a good thing.

Most important of all: once you begin working with the silicone, you absolutely must complete the entire job in one go, all at once, not letting the silicone begin to cure or skin over. Silicone sticks to most things, but one of the big exceptions to that is...old silicone. If you let the initial adhesive bead dry, and then try to coat the bottom, the new will not adhere to the old; you might not get a leak, since the original bead should be waterproof, but you will have water making its way into the joint and contacting the metal. Do it all at once and you will end up with a continuous waterproof layer of silicone completely covering the bottom and extending right under the glass to adhere the two pieces together.

A further refinement would be to carefully cut a glass disc that would fit the bottom, and then drop it into place immediately after the cylinder is lowered down onto the original bead. Then, run another bead all the way around the seam and finish it with your finger. This would have the advantage of giving you a smooth clean glass bottom rather than a rubbery silicone floor, but would require you to either cut that perfect disc yourself...which I wouldn't even try personally, based upon my glass-cutting skills...or to pay a professional to do it, which will likely cost way more than the rest of the project combined.

Again, this is what I would attempt; you take full responsibility for it if you try. My suggestions all come with a 100% money-back guarantee; your money cheerfully refunded if you decide you don't like the results. Good luck, and keep us posted on developments!

Edited to add: This is actually glass, right? All the previous blather above is based upon this being glass; if it's acrylic or some other substance, forget it; silicone won't work.

 

[Backfromthedead]

You could try the pond shield. That would be the quickest, easiest thing, probably even cheapest. You could silicone the glass to the metal beforehand as well. Silicone doesnt bond to metal like it does glass but still sticks to it.

 

[Lepisosteus]

Take it apart and buy a a piece of 1/4 glass cut same size. Mirror shop $20

 

[jjohnwm]

This was supposed to be a cheap project.

Silicone floor: costs a tube of silicone.

Pond Shield: costs whatever the smallest quantity of Pond Shield costs...plus you still buy the tube of silicone.

Pre-cut piece of glass: costs $20 (?)...plus you still buy the tube of silicone.

 

[esoxlucius]

Honestly, just go to your local LFS and buy a ready to rock 'n' roll goldfish bowl. I wager it'll be cheaper than doing something with that. Use that for something else.

 

[LukeOscar]

certain grades of stainless steel are fine for aquarium use. could be possible that it doesnt need anything?

 

[Tetra Studio 60]

Woah thank you all so much for the differing ideas for this! What I'm going to go forward with is first calling some local glass and mirror places and checking pricing (I know some things are unfortunately just quite a bit more expensive in Canada), and then if I can't source anything well priced, I'm going to go forward with jjohnwm's idea with the silicone and just give it longer to get established with just plants, and monitor it for a while before/if I introduce shrimp. I would love to get the glass bottom so I have the option of going with a rimless look but as the saying goes, in times of need, even the devil eats flies. I have a wealth of tools including some good non-abrasive paste spreading tools so spreading the silicone across the bottom shouldn't be all too difficult, and I figure I just do it thick and err on the side of caution.

Thank you all so much for contributing, I'll be sure to post updates as it progresses!

 

[Tetra Studio 60]

Just wanted to update you all, I ended up finding a place that cut the glass for me for $30 (he gave me $10 off just cause he loved the idea, what a great guy) and I just finished joining it to the main glass cylinder. It honestly wasn't the best bead I've ever drawn but the angle made it difficult and I figure I'll just clean it up with a razor after it's cured.

Unfortunately the decision on keeping the original metal bottom was made for me, as the cut glass is just a millimeter or two too large for it. I'll post tomorrow to let you all know how the water test goes!

 

[Backfromthedead]

Just wanted to update you all, I ended up finding a place that cut the glass for me for $30 (he gave me $10 off just cause he loved the idea, what a great guy) and I just finished joining it to the main glass cylinder. It honestly wasn't the best bead I've ever drawn but the angle made it difficult and I figure I'll just clean it up with a razor after it's cured.

Unfortunately the decision on keeping the original metal bottom was made for me, as the cut glass is just a millimeter or two too large for it. I'll post tomorrow to let you all know how the water test goes!View attachment 1517309

Excellent! For best results give it at least 3 days to cure ime. That glass doesnt look too thick but it still could take a few days for the silicone in the middle of the seam to cure.

The top steel piece could still be very useful to brace the tank.