I have an old 100gal tank

[Zclover95]

So I have an old 100gal tank that I used as a terrarium for a couple years that I want to redo as an aquarium and upgrade from my 50 to the 100.

My questions are, it has an odd chunk broken off near the corner, that did not go all the way through or leave spiderwebbing of any sort but could damage like this cause some structural integrity I should worry about?

Next is the middle cross support piece broke in half and so there's nothing holding the middle together, should I replace that? And how would I go about doing so?

Now for the actual setup questions, I currently run a 75 and 50gal sponge filter on my 50gal and I have 3 Cory cats and 2 discus that are both about 4-5in and do probably a 98% WC twice a week. Now I was wondering with that setup could I get away with 3 or 4 WC a week at 50% and put some more discus in without polluting the water?? I do construction 10 hours a day 4 days a week and doing a WC when I kick my boots off when I get home can sometimes be the last thing I want to do so i definitely do not want to over populate lol.

Pic related; the crack in my tank
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[Adam S]

Imo, replacing the cross brace, replacing the silicone seal, and hoping the chip holds is roughly equal to the cost of a new 125 or 120.

[LizStreithorst]

It looks to me as though it is the long side of the tank that is cracked. I would not trust a tank like that.

If you live close to TN you can drive to Glass Cages and pick up a front panel for not a ton of money. If you buy the glass at a glass place it will cost more. You will have to rebuild the entire tank, but since the tank is old it will need to be resiliconed anyway. It can be done because I have done it, but it's a big job.

The top brace is easy. Just silicone a glass brace in the middle instead. It will last forever.

If you're a construction guy I'm sure that you could get it done. It just depends on weighing the cost of replacing the entire tank with your time and labor of doing it yourself.

[fljones3]

Imo, replacing the cross brace, replacing the silicone seal, and hoping the chip holds is roughly equal to the cost of a new 125 or 120.

I agree. I would not trust it even if you could repair.

[LizStreithorst]

I've resealed tons of them. It's no big deal. Just a lot of labor.

[Adam S]

I've resealed tons of them. It's no big deal. Just a lot of labor.

This. That being said, we're assuming the OP knows how to/is willing to reseal. Rebuilding the tank and replacing the front pane though... thats a LOT of hours with acetone and steel wool. Not even including the 1-2 week cure time for quality RTV. The cost of a new 125 is cheaper than the number of hours needed to fix that tank, especially if the OP hasn't done it before.

[LizStreithorst]

I suppose so. But the OP said that he was a construction guy so I figured he'd have the clamps and the know how. I guess it comes down to how much money he has and the cost of the replacement glass. I never used steel wool, just razor blades and acetone. I let it cure over a long weekend before I filled it with water and tested it. This was about 18 years ago and the tank is still holding water.

[Willie]

I have an old 125 gal tank with a broken brace which I use only for conditioning water. I drain that tank daily for water changes and the tank flexes about 1/2" between fully and nearly empty. It's held with no problem for 4 - 5 years now, so I don't even think about it any more. That said, I wouldn't do this for a tank with fish in it, but this is an old version with extra thick glass.

I purchased a new 125 (another conditioning tank that cracked) a month ago for $280 locally.

Willie

[Altum Nut]

I have a 112g tall 30"x18"x48" where center brace cracked as well Willie. I just got a metal flat plate to brace it when I noticed the 1/2" bow that scared the life out of me. Been holding up for 2 years now without issues.