Weld-on #40 to fix crack in eurobrace acrylic

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davenmandy

Peacock Bass
MFK Member
Feb 1, 2012
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Moving my tank resulted in a 6 inch crack running from the corner of my eurobrace (rounded corner) towards the back corner of my tank. I unfortunately can't move my fish anywhere because they are 3 large rays and noone will take them. I have drilled a small hole at the tail end of the crack to prevent further spread. I am wondering first of all how worried I should be about leaving this tank up and running? The crack doesn't seem to be spreading in the 20 hours its been there, but I'm paranoid about turning my hosue into a swimming pool while I'm at work. Second of all, can I patch this crack while the tank is filled (obviously not to the top)? At least from the top for the time being? I only have 1/8th thick acrylic, should I double it up before patching, or should I double i apply the first 1/8th at the top of the patch and then double it up after? Any other suggestions? This really sucks. Brace is 1/4" thick, tank is 7x4 and 2'tall, made of 1/2" acrylic.

IMG_20141116_095457.jpg

IMG_20141116_095457.jpg
 
Oh and another question, I cut a 6 inch by 1 inch strip to put over the crack. Should I make the patch wider? The weld-40 shipped from Toronto today, I would hope it's here tomorrow.

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I was going to do both, but if it doesn't matter structurally I'll start with the top and do the bottom during a bigger water change (fish stressed from the move). I noticed you had a big sheet of acrylic for the scratch, mine was literally a 1 inch piece i was just going to put along the length of it, would you advise that I use a bigger piece?

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I really hope I don't have to empty it to patch, but in my head I am thinking if now there is extra pressure applied to the seams, if i patch it while the pressure is still there then the pressure would continue to be there even with the patch, so therefore the patch wouldn't support much? As in, if the tank is bowing more now hypothetically, if i patch it while it is bowed, it will continue with that bow and the patch wouldn't be useful other than sealing the crack, am I right on that or is the amount neglible considering the crack size and the fact it didn't hit a seam?

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Maybe someone else would like to chime in.

You said that you stopped the crack from going any further by drilling a hole. That was a good idea in my opinion. If you go with a larger patch anywhere from1/4 to 1/2" thick, I think you would be fine.

I would recommend removing the fish and draining your tank as low as possible before performing the repair. It will take at least 12 hours for the repair to cure. During that time I would not want a lot of stress on that area.

I would get some plastic garbage cans, a large plastic water trough or even a kiddie pool to use for a holding tank for a day or two. Make sure to purge your fish for a couple of days before doing this. They will need good aeration you could go as far as putting a good canister filter on it also.




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Thanks for your reply Scott. I just moved these guys and tank from house to house. I purged them 4 days before the move. They ate yesterday and today. Obviously not very comfortable having this tank running with a crack for a longer period of time. What I would like to do is patch it on top when I get the bonding agent tomorrow for some security, then on the weekend when I don't have to work drain it as much as I can, say 80%, put the rays in totes, and patch the bottom. These guys have gone through a lot of stress last few days, and i cant really accommodate being near the tank for 12 hours during the work week, though possibly Wednesday or Thursday I could use a vacation day.

Now here's the thing, I know WO40 kind of melts the acrylic in order to bond it to my understanding. If I attempt to put the bonding agent over the crack while the tank is still filled in order to try to patch the top, would the breakdown of the acrylic coupled with the pressure the water exerts essentially separate the crack even more, leading to total disaster? As in would the "melting" acrylic around the crack be further separated by the weight against the brace and not successfully patch? Again this just being a temp fix till such a time as I could patch underneath it with the tank drained.

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I have to agree with Scott, this repair should be done with the tank empty. The pressure is just pulling the crack apart, it should be as together as possible before applying the patch. I would also go for a wider patch, as well as a thicker one. I would honestly go with a 1/4" or 3/8" piece that extends a few inches past the crack on all sides possible. It would be best to do the top and bottom at the same time as well. If you do them at separate times with the water level at different heights the patches will have different pressures on them when empty and full, stressing them differently.

I know it isn't what you want to hear, but I feel like it is a bad idea to patch the tank full. Also, 1/4" seems really thin for a brace on a tank that large.
 
Thanks for the input. I hate to say it but I agree with you. Earliest possible I could do this is Wednesday. I will be doubling up the 1/8th acrylic to make it 1/4, probably a tiny bit less when I apply the wo40 but that's all I can do, maybe I can triple it up. How safe would you say the tank is to sit until Wednesday? How about the weekend? How long will I have to cure this, 12 hours as suggested before or any less? Anything I can do to speed up the curing? Any advice is welcome, I'm trying to avoid a tragedy here as best I can. Empty 100% of it, or would 80% do? My rays are going to hate me.

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I agree with the other advice given... i will say that drilling a hole in the end of the crack to stop it spreading is the right thing to do. Nice work. Def. A good idea to do a full patch/repair when the tank is dry but you've potentially solved the problem already so u can continue the repair any time down the road at ur convience. Its not detrimental. I have a 180 with a crack in the top brace. I drilled the end of the crack 5yrs ago with the tank full and left it at that. Its only 4-5" and i never got around to finishing it. Hasent spread since.

Weldon #40 also takes a full 72hrs to cure not 12.... so this is a full tear down project, not a quick fix with the tank drained to any level. Id throw the fish in a temp pond/pool and give the glue a good 2-3 weeks to dry best case scenario. If u dont have the means to place the fish elsewhere for the repair id stop at where u are now until u do. Your efforts will be wasted if the glue doesnt harden up properly in humid conditions around water.
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