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Discussion Starter · #1 ·
So I bought a 75 gallon tank for $75 and was assured it had no leaks, tonight I filled it up, and sure enough it sprung a leak. Its a really old tank and the glass is 1/2" think, which is thicker than usual I think. There are some chips in the glass in some places but I don't think that is the problem. The problem was on one of the corners the seal was bad.

I have a few questions:

Has anyone dealt with an older tank using the thicked glass like this before? Is it any different than resealing any other tank?

Do I need to take the thing apart entirely, apply silicone between where the glass fits together and also seal it like normal, or should I be okay just removing the seal on the inside and resealing that?

Is there anyway I can just remove the old silicone from the corner where the leak is and leave the rest intact?

Has anyone had any luck just getting a glass company to reseal it for cheap?

Thanks!
 

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Unless the silicone holding the tank together is failing, a reseal of the interior is all that is necessary. To determine if the silicone between the glass pieces is losing it's grip. Try spreading the glass; it really shouldn't move.
I have a tank that I built over 40 years ago that is still holding with the original silicone, so probably, your okay there. Keep in mind that a tank made with 1/2" glass has more silicone between the panes than one made with thinner glass.
There is no difference in the sealing operation between thick and thin glass, other than you may want to run a biiger bead on thicker glass. Regardless, the procedure is the same. Strip all the silicone out of the inside using single edge razor blades. It is important to get it all. When you are positive you got it all, take a new blade and go over it again. Before applying silicone, the area needs to be cleaned well with alcohol or acetone. If you aren't comfortable with your ability to do a clean job when finishing the bead, mask the areas you don't want to get silicone on. Get some GE Silicone I for windows and doors, and practice how you will apply it. On bigger tanks it helps if you have someone to give you a hand to turn the tank, to make the job easier and faster. Once you have applied the silicone to all seams, you need to smooth it using a spoon or as I do, a finger or thumb. If you applied masking tape, remove immediately.
The job may seem daunting the first time, but really, it isn't that difficult. Almost every tank I have was bought as a leaker, at a reduced price. As well I have built 5, the oldest being 40 years old.
Around here, Big Al's sells new 75 gallon Perfecto tanks for $89 during boxing week. So, you have to determine for your self whether a reseal is worth it. Personally, I like to reseal rather than see a tank go to scrap.
 

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Discussion Starter · #3 ·
Thanks for the reply.

Where the leak is, the glass is definitely coming apart. Its not noticeable empty, but when it filled that's definately why it was leaking. Is it possible for me to just reseal that one corner and then do the inside, or do I need to just start completely over, remove every bit of silicone and start from scratch?

I'm thinking that maybe I could just reseal that corner and then let cure, then stripe the inner seal and redo that?

I have resealed a 20 Long, and actually that was my frist tank upon re-entering the hobby. It didn't look that great but the seal has worked. I got the hang of it towards the end, and I will definitely used a spoon and masking tape this time.
 

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The fact that it is coming through a spot in the seam between the panes doesn't mean it has failed. Strip all of the silicone from the inside, and see if the glass can be moved. If it can't, you should be able to get by with an interior reseal. If it looks like it is failing, I would dismantle and redo the whole tank. Does it have a one piece top and bottom frame or does it have 4 trim pieces (or no trim)? It is difficult to make a judgement without actually seeing the problem. i just redid 2 tanks, and the trim came off with no effort while handling the tanks. I wouldn't normally remove them to do a reseal. A 75 made from 1/2" glass is definitely worth saving.
 

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Discussion Starter · #5 ·
Strip all of the silicone from the inside, and see if the glass can be moved.
I can move the glass as it is now, without removing the inner silicone haha. The trim is comming off at all corners now. This thing was sitting on a porch for the last year (or more) so I'm sure that it being old combined with weathering the seasons finally took their toll, along with being moved.

I'm off on monday, so that might be the day I try and get this done.
 

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If it's clear silicone, UV light can destroy it over time. A sunny porch in Alabama would be enough I think. At least the silicone should be easier than average to scrape off and rub away the residue. Using damp table salt as a mild abrasive can help with the clean up of the glass panes.
 

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Some aquarium maintenance companies dabble in tank repair on the side but I don't think you will find a tank manufacturer who will "remanufacture" a tank.

Resealing a thick old tank may be different in the way the pieces are assembled. Be sure you know which pieces came from where and in what order you had to take them apart to avoid chipping. Notice if the sides rest on the bottom or if the bottom "floats" inside the walls.

If the plastic frame is faded, you can paint it with a plastic paint like Krylon Fusion, or if you want it to look more original, use liquid shoe polish on the outside, black, brown, or tan as appropriate.
 

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Discussion Starter · #8 ·
It is an old frame with four pieces attached together all around the top, and I would assume the same for the bottom. There is also no center brace (I've been trying with no success to locate a glass canopy for this, so I think I'll have to have one made). I'm going to strip all the silicone tonight and try a reseal tomorrow. I'll be gone the next two days after that so hopefully it will cure and be good to go next week.

If anyone else has any ideas, or pointers please let me know.

Thanks for all the help!
 

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If you wish to add a centre brace for the purpose of holding glass lids you can do so, with a piece of glass; doesn't need to be 1/2". It has the advantage of not blocking light to the tank versus a plastic brace.
 

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Discussion Starter · #11 ·
Any tips on how to get the glass panes apart? That one corner is loose, but the rest are solid as a rock. I can't even get the rest of the bottom frame off, just the end where the pane is loose.

Also, there are several chips and imperfections in the glass, is this going to be a major problem?

Thanks for the help so far.
 

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The usual method is to use a fine wire such as a guitar string or piano wire. Fishing line will sometimes work but usually ends up getting cut on the edge of the glass. I would try to work the razor blade into the joint to at least weaken the silicone. Go slow and easy, although with 1/2' glass it won't be easy to break. Once one pane is out, it usually facilitates removal of the rest. have lots of blades as you will probably break a few. If the chips are on the edges, it is usually not a problem. Sometimes, you can reverse the pane to hide the chips in the seam. When you get it apart, spend some time making sure all the silicone is removed fron the ends of the panes.
If you add a glass brace, it is customary to attach it up tight to the trim, and siliconed to the tank. It should be covered by the trim so won't be noticeable. I recently added a glass brace to a 90 I resealed (bought as a leaker) as the plastic brace had a crack in it. Rather than wait for it to fail, I added the brace (3/8") as a premptive measure. It isn't visible from the front, as the trim extends down far enough to hide it.
 

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Discussion Starter · #13 ·
Since its just the that single corner that's loose could I just unseal it and reattatch it, or is it just wise to go ahead and do that entire thing?
 

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While it might be possible to redo only the one pane, it would be difficult to ensure a good fit, especially if it is an end paane. You would still have the problem of new silicone meeting old, and no way to ensure that any voids are filled between the two. You would be reying on the inner seal to hold the water, when in fact it is really just insurance. the tank should hold water without it. That would be the ideal situation, but it isn't always the way it is. Any tank that leaks has a void somewhere between the panes. So, while it is a much bigger job to totally dismantle the tank, you will end up with a more secure assembly, and should have many trouble free years of use.
Take the time when dissassembled to remove all the old silicone from the edges. Flip the bottom over so the sides go on new glass. It isn't necessary to have trim on the bottom of the tank if you set it on styro. The main purpose of the bottom trim is to lift the bottom pane up off a solid base so a small piece of gravel or something can't get between the base and the bottom and create a point load. Styro will absorb any small bits of debris, and will also absorb any discrepencies in flatness of the base you put it on.
 

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I would never use guitar string to saw through the old silicone. The beauty of monofilament line is that it does break when pinched or angled wrong. Guitar string will create gutter marks, shallow chips where ever there is a tight spot, and I figure AU figures there are already enough chips on the glass. Every time the monofilament breaks, you just pull more off the spool which i always set in the tank.
 

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BillD
I have a 125 that the silicone has come apart between panes of glass. Does that mean I need to completely disassemble the tank in order to reseal it? (this has been answered and the answer is yes) I have never done this before and am more than a little nervous about how it will turn out. Do you have a procedure that works that you would be willing to share? How do I get the thing back together and square? It seems to me that I will just have a bunch of loose pieces of glass that I am trying to glue together. Do I tape it together for the prefit then run the silicone? Thanks
 

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If the disassembled tank has plastic frames, you use those as "jigs" to hold the glass pieces in place. Squirt in the silicone, leading a bit of it ahead of the spout as you push forward. Not so much it gloms off, but if it does, don't touch the spillover. Leave it. It will razor blade off clean once it cures all the way.

Wherever you see bubbles of air in the silicone on the wall corners, use some clear parcel strapping tape on the outside to squeeze them out. I would strongly suggest euro-bracing on the tank bottom. This is flat glass strips the same thickness as the tank flat on the bottom set against the walls. You push these in soon as you bead the bottom, then do the walls. This gives you a purchase on the walls above the previous joint. Virgin glass is always better than the best cleaning job.
 

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As for the cross piece, you more than likely don't need one on older 75. Unless it's for supporting a lid. I have a 75 that is at least 30 yrs old without center brace. I've moved it many times by myself, it's sat empty for years at a time [Always indoors though], and it's never been any trouble.
 

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AU Chief said:
Thanks for the reply.

Where the leak is, the glass is definitely coming apart. Its not noticeable empty, but when it filled that's definately why it was leaking. Is it possible for me to just reseal that one corner and then do the inside, or do I need to just start completely over, remove every bit of silicone and start from scratch?

I'm thinking that maybe I could just reseal that corner and then let cure, then stripe the inner seal and redo that?

I have resealed a 20 Long, and actually that was my frist tank upon re-entering the hobby. It didn't look that great but the seal has worked. I got the hang of it towards the end, and I will definitely used a spoon and masking tape this time.
If you can thread some monofilament fishing line through the leak and scrape all the old silicone out with it, you could try fixing just that one area. i've done it on shallow tanks and would probably try it on one of my own tanks, but not one that I was repairing for someone else. It is more likely to work on a new tank because the other seams are good and there was likely a factory flub on the seam that opened. With an older tank you don't know how close behind the other seams are to wearing out.
 

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Braided fishing line, 60lb, worked a treat. WEAR GLOVES!!!!!!!!
I second no guitar string, those chips make me lose sleep!
 
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