Aquarium repair??!!

[Slipstreme]

Hi there,
I just joined and I am in need of aquarium repair advice. I have a 20 year old oceana 1/2 circle 70 gallon tank, with a central bulkhead and a 40 gallon sump that is equally as old. It’s been a successful and happy cichlid tank for the duration, but I decided that it needs redo-ing, and I wanted to check the integrity of the seals for a tank of this age. Anyway, I have not fully drained the tank, but I drained the bulkhead and the silicone in the bulkhead is super rotten. So I’m knowing right away that it will be likely that I’ll have to fully drain and dry the tank, remove the inside silicone and reapply, but I’m also wondering how to successfully refurbish the rest of the seals, even if they look solid and intact. Can I apply thicker silicone to the inside of old silicone, or would that possibly make a problem? Do I have to completely remove all the seals even if they look good? Advice is highly appreciated. I shudder at the thought of 70 gallons of water ending up on our floor if I do this wrong, or if I leave it and the seals start to give way… I’ve attached a pic of the bulkhead, and a pic of the tank before I disassembled it (no fish atm)
Tyia for your advice!!!

[Andy Sager]

When it comes to resealing a tank, you could put more silicone over the existing silicone however, 1, it's not going to look pretty, 2, if you don't make good contact with both panes of glass you have done nothing and 3, if there is any major gaps in the seam, doing this is not really going to solve the problem.
You would need to take the existing silicone out but don't need to separate the glass panes. Take a single edge razor blade and run it from the top then bottom then you should be able to pull the bead out. You would then take a tube of silicone and run a single bead of silicone the length of the side. After that, you take a wet finger ( you can also wear a latex glove and moisten the finger) or caulk finishing tool and press the silicone into the glass. I have known people who will use the blue painter's tape, placed along side the existing silicone before removal, so that they have a guide as to how much silicone to use. Once the silicone is "tooled" and still wet, just remove the blue tape so you have nice lines.

With all that said, I have 40 year old tanks ( a 40, two 30s and 10 gals) that sat dry for almost 20 years that didn't leak when I reset them up. Silicone does not shrink over time and if your tank still has some water in it, the chances of you having a problem is small. ( granted, not 100% but small.)
The silicone in the bulkhead area does look rough but I'm not sure why it would unless it was a repair with poor quality silicone. I would tackle that for sure. Unless the tank seams look like the bulkhead seams, I would leave it alone (but I won't have to face the 70 gals of water on the floor is there are bad seams. ) One of the other issues is when you move a tank, you can change the stress points which can cause the silicone to separate from the glass so you really need to know what you are doing if you are going to redo the whole tank.

Hope this helps.

[Colin_T]

I don't even know what that bulkhead thing is or how it fits in the tank, let alone see any silicon in it. How do you know thew silicon is stuffed?

Good silicon will be firm but slightly squishy. There should be no cream or white patches in the silicon and no bubbles in it.

Bad silicon will be hard and brittle and could have cream or white patches or bubbles in it.

If the tank is still holding water, there shouldn't be any need to reseal it.

[Slipstreme]

Originally Posted by Andy Sager

When it comes to resealing a tank, you could put more silicone over the existing silicone however, 1, it's not going to look pretty, 2, if you don't make good contact with both panes of glass you have done nothing and 3, if there is any major gaps in the seam, doing this is not really going to solve the problem.
You would need to take the existing silicone out but don't need to separate the glass panes. Take a single edge razor blade and run it from the top then bottom then you should be able to pull the bead out. You would then take a tube of silicone and run a single bead of silicone the length of the side. After that, you take a wet finger ( you can also wear a latex glove and moisten the finger) or caulk finishing tool and press the silicone into the glass. I have known people who will use the blue painter's tape, placed along side the existing silicone before removal, so that they have a guide as to how much silicone to use. Once the silicone is "tooled" and still wet, just remove the blue tape so you have nice lines.

With all that said, I have 40 year old tanks ( a 40, two 30s and 10 gals) that sat dry for almost 20 years that didn't leak when I reset them up. Silicone does not shrink over time and if your tank still has some water in it, the chances of you having a problem is small. ( granted, not 100% but small.)
The silicone in the bulkhead area does look rough but I'm not sure why it would unless it was a repair with poor quality silicone. I would tackle that for sure. Unless the tank seams look like the bulkhead seams, I would leave it alone (but I won't have to face the 70 gals of water on the floor is there are bad seams. ) One of the other issues is when you move a tank, you can change the stress points which can cause the silicone to separate from the glass so you really need to know what you are doing if you are going to redo the whole tank.

Hope this helps.

Thank you it did greatly! Your reply was greatly appreciated, I was stymied in the last month by -20 weather, which has had no break, but Sunday it finally warmed up to close to zero, so I could fully drain the tank and sand outside without fear of creating a giant dangerous skating rink on my front step. But after draining it and getting rid of the sand finally, I also discovered that my husband using pot cleaning pads to clean the glass has left huge massive amounts of gauges all along the inside of the glass… so I’m now also attempting to refurbish the glass in addition to the silicone. The silicone all around the bulkhead is indeed rotten, I have no idea how, as it was a brand new tank when we bought it, and should have the same silicone in the bulkhead as the seals, but now I’m a bit concerned if I try to remove the interior silicone from the bulkhead, it will not seal properly unless I do the entire interior, as the silicone intersects at the base of my tank. Anyway, I suspect I either have to remove the bulkhead silicone or the entire inside of the tank,. The silicone on the front might be peeling, so I’m leaning towards the entire inside of the tank, to do a complete refurbish, but I’ll have to wait on that currently, until