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Discussion Starter · #1 ·
I never owned an acrylic tank before, always glass, and even glass and plywood but never acrylic. Anyways usually when I buy a used tank I would run a bead of silicone along the inside seams before I fill, but I do know silicone doesn't stick to acrylic so what could I do to this tank?

Brief history: I found a 300 gallon acrylic tank on kijiji for an extremely decent price, I have no room in my home as of yet for tank so I started building an extension on my home just so I can bring it inside. I have stored it outside for 2 months wrapped up in tarp and now it's starting to get cold out, however, I should have it inside in only a few more weeks.

Because the tank is used plus I had it outside I have worries after seeing YouTube videos of tanks flooding homes. I really want to make sure this tank will not do that so is there anything I can run along the inside seams to ensure there is no leaks before filling tank?
 

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I don't remember the name of the product, but it is a liquid that is applied to the seams via fine needle and bottle. It bonds the two pieces of acrylic like a weld. If you youtube making acrylic fish tanks they will show you and explain everything better. It's 5am my gray matter isn't working yet.
 

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Tensol is one of the products for acrylic, but the Tensol I received was much thicker than the very runny stuff I'd used before. The acrylic products are different than epoxy however, and work by melting/fusing the edges together, instead of themselves acting like a gap filler like silicone does.

Anyone, would acrylic cement or epoxy work better for resealing/adding additional seal to an acrylic tank instead? I'm not sure what the potential is for either of those to leach nasties however. As such I'm considering hot glue instead even, which seems very non-toxic in everything I've read and of course wouldn't be appropriate for building tanks but might work on acrylic just to add a little extra security. It can be a little messy if you're not careful though, but in my instance that's not so much of a concern with this specific breeder tank.

And I need to do the same thing after buying a 13g acrylic display case which I'm converting to a tank but which has a small leak currently along one edge.
 

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Yes, Weld-on. You apply it with a needle dropper bottle. The PCs need to be clamped tight and it will draw itself into the gap. It's thin like super glue and will not fill gaps. Once it's welded on, it is not coming apart ever.

ibmikmaq - I'd tell you to just fill it outside on a level surface, if it holds water outside you should be good. One of the big draws of acrylic is no silicone glue lines... that and 300gl really doesn't weigh that much.
 

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Anyone ever use superglue/Cyanoacrylate on acrylic tanks? The OP (and I) are looking for a gap filling adhesive more so than a primary bonding agent, (which could thus compromise the original seal). Superglue can cloud plastics so any areas to not be glued should be masked off appropriately though. -

Loctite 3090 Instant Adhesive - Gap filling, 2-component, low bloom

The new multi-material adhesive Loctite 3090 unites the best of both worlds: faster than an epoxy and more gap filling than an instant adhesive. It brings advanced technology to your workshop - for a faster, easier and more efficient job and quality results.

Gap filling: Up to 5 mm

Fast-curing Fixture time: 90 – 150 sec.

Multi-Substrate: Well suited for rubbers and for porous and/or acidic surfaces
Suited for plastics, metals and for polyolefines in combination with Primer Loctite 770 or Loctite 7239
 

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If the gap is in an area that will not be visible, you could use a two part, 5 min. epoxy. It will fill the gap allowing you 1-2min. to mold/shape. It will dry amber color.

Anything other than Weld-On, I would follow up with a coat of silicone.
 

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If the gap is in an area that will not be visible, you could use a two part, 5 min. epoxy. It will fill the gap allowing you 1-2min. to mold/shape. It will dry amber color.

Anything other than Weld-On, I would follow up with a coat of silicone.
Isn't the silicone useless though as it won't remain sufficiently securely attached to the plastic in the long-term? And the last time I used epoxy it still smelled chemically for days and weeks afterwards...
 

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I used silicone to place a false wall in am acrylic reef tank, it held for 3yrs until I took that tank down. It was in place to hide plumping NOT intended to be water tight.

If your research says silicone won't be water tight on acrylic then that is a good contribution.

I've used Dow's 5min. epoxy on various projects. Yes, there is a smell until it cures. I've never had the oder linger more that 15-20min. I just took a 40gl acrylic on trade the previous "abuser" of this tank used epoxy to repair a crack on the top near the filter cut out. Looks terrible but it does hold well.
 

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I would strongly recommend against using anything other than a weldon type product for acrylic seams in a display tank, let alone a large display tank. There are different types of weldon, #16 is thick, thicker than syrup and comes in a squeeze tube, where #4 is like gasoline and is applied with a needle applicator.

Other products will/can cause crazing and could cause failure, weldon is not expensive and I would not risk using something like epoxy that could have an unknown chemical reaction.

If the tank needs to be "re sealed" the only way to do so would be to cut every panel apart with a router or saw (router with a flush bearing is best)184, prep the surfaces and re-glue with weldon. Typically acrylic tanks are never re-sealed as the bonds are chemical and the level of effort to do this is non trivial.
Also the good thing about acrylic is that the seams are crystal clear, if there are any issues with the seams you should be able to visually identify them.

If you can post a picture of the trouble areas it should be easy to tell if its repairable, otherwise adding a bead of weldon will do little if anything to help out structurally. The chemical bond of acrylic to acrylic is much stronger than the adhesive bond between glass and silicone.
 

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Fill the tank, if it doesn't leak, do no screw with it. You will not be happy with the results. Acrylic tanks are easy to tell if there are a problem. If it "looks" cracked, it is stressed. Joints should be clear.
 

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Yeah, you can't just reseal an acrylic tank. If it holds water you will likely only weaken the tank by messing with Weldon and the seams. Check for crazing, do a water test and leave it at that.

Hot glue will be useless, as well as silicone. Epoxy might add strength but will look terrible. Even adding silicone to a glass tank without properly stripping the seams will, at best, only mask the problem for a while. Instead of sprouting a leak it may clog a potential one until the structural seam totally gives. Your new sealing job won't do much of anything it the joint between panes fails.

If you don't know what you are doing with acrylic you will likely only make things worse. If you really need to reseal it you will have to cut it apart and build a new tank.
 

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Discussion Starter · #15 ·
Ok thanks for all the tips I will set it up outside and fill it with water on Monday! I will post my results with pics!
 
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