Repairing a crack on 725 gal acrylic tank

[ptomoson]

I'm looking to buy this 8ft long by 4ft high by 3ft wide tank but would like some advice on repairing a crack along the bottom caused by the weight of the tank being sat on the ground with the bulkheads still in place. You can see the crack in the bottom right and along the bottom.

This was a freshwater setup that came out of a restaurant. Large sump, bulkheads and stand included.

The crack doesn't go above 4 inches from the bottom so the guy selling it was going to cut the bottom 4 inches off the tank and replace it with a new piece of 1" acrylic. He already has purchased the 4' x 8' piece of acrylic.

My question is what would you do?

I was thinking if I could repair the crack without cutting off the bottom I would just put a 4 or 5 inch sandbed in the bottom or possibly trim the bottom with something so the cracks do not show.

Thoughts?

 

[ITR]

That tank is deep! What are you using it for? Fish only? A reef?

If it is a for a reef, you are going to need some serious lighting to punch through to the bottom. If it will be a fish only tank, I could understand why you want the space, but even then...that tank will be a challange to maintain.


I'd personally cut the bottom of the tank out like you suggested and install a new piece. Just my 2 pennies.

 

[teesquare]

And - HOW will you be able to keep it clean? Maintenance on a tank that tall is a royal pain in the buttocks!
I would recommend that you cut it down in height to the point you can reach the bottom of the tank, without putting on a scuba mask!
Then use the cut-off portion ( after repairing it) as a sump.
T

 

[hoosierpat]

Bad spot for a crack, I'd trim the bottom above the crack and weld a new bottom on.

 

[marekt]

I would call acrylic tank manufacture and ask them

 

[mdntrdr]

Bad spot for a crack, I'd trim the bottom above the crack and weld a new bottom on.

I agree.

 

[ptomoson]

Bad spot for a crack, I'd trim the bottom above the crack and weld a new bottom on.

I guess I would rather have the crack along the bottom than along the top. Why not patch the crack and setup a DSB? Seems like cutting and welding on a new bottom would be quite the project. I plan on a FOWLR for this tank.

He wants $500 for the tank stand, sump, bulkheads and whatever else he can find. Sound like a good deal or not worth my time?

 

[greatXss]

The crack on the bottom is so bad because you have all that weight pressing on it. I would cut the tank down to a more manageable size and weld on a new bottom as suggested earlier...just my .02

 

[DJ_drew]

buy fix sell make some money, i agree cut the bottom and re do it! but if ur up for the challenge of a tank that tall go for it! would be a heck of a build!

 

[hoosierpat]

The crack appears to be primarily along the bottom seam, maybe slightly above it. That makes it hard to patch. I mean realistically how would you patch it? The good part is that it is easier to cut and reweld a new bottom than it would be a new top. Plus, you already have the bottom cut if you buy the tank. I've seen big acrylic tank seams fail and it isn't pretty but it happens very fast. Think about how much pressure is on the bottom seam and then how long it would take to clean that mess up before you think about shortcuts, its not worth it, trust me.

 

[Lacy]

It also looks like it is going to need some serious polishing which can be very time consuming. I also agree deep tanks are a royal pain. I would cut it down. You might want to keep looking. With the economy there are alot of deals out there.

 

[Untamed12]

I don't build acrylic tanks for a living...but could you not just wick some methyl chloride into the crack? That should seal it right up just as if it were a regular joint in acrylic. Maybe go over the seam with some thicker Weldon to ensure that part is good.

Then...fill it up outside the house! Would I ever trust it?...probably not.