45 gallon aquarium rebuild

A good friend of mine gave me a couple of larger fish tanks. The one I have had up and running for a while now. The other didn’t make the move from his place to mine. It sprung a leak. It held water when he had it, but leaked when i tried to fill it up.

No biggy, I can fix that.



All Glass Aquarium build on May 12 1986 Here you can see that the tank is 23 years old. hopefully my patch job will last 23 years!

Filthy Dirty fish tank The tank is… dirty. Filthy dirty to say the least. It was in his basement running. I don’t remember if he never put fish in it when he set it up or if the didn’t survive, but he let the tank evaporate down to 4-5 inches left in the tank. So needless to say it was a little crusty. I also stuck it in the mud when I was moving it, so it’s literally dirty to boot.





Using a razor blade to cut away the silicone sealant on an aquarium To to remove the existing silicone sealant, I use one of those metal backed razor blades. I find the holder gets too clumsy in the corners, so i just be careful. You slide the blade down along the glass. It can be a bit awkward at some angles, but if you can use both hands, you can do it pretty easily.

Silicone seal partially removed Just cut the sealent clean to the corners, scraping the class clean of the old silicone.


rebuilding a leaky fish tank The corners are a bit fussy. Just hack and slash that stuff out of there, and clean it up well once the bulk of it is gone. Scrape all the thin stuff that clings clean with the blade. Just cut it off like your shaaving, or sharpening the blade on the glass.

the corner of the tank cleaned, ready to be cut awayHere is a cleaned corner, ready to be cut. Notice the blue tint to the silicone? I am thinking somebody treated the tank for ich once or twice. Probably not too many times, and a long time ago at that. Probably in the first 10-15 years of the tanks life. It’s not very strong colored, and isn’t behind the sealant where it’s loosened off the glass.

removing the silicone from the leaking aquarium Here I am pulling a strip free.

The fresh new silicone fixing the leak in the aqiarium The new silicone seal. I put it on, and smothed it with my finger. You can use a medical clove it you don’t want the silicone on your hands. It’s a pain to get off. Best way I have found is to go play in the dirt.


partially filled, very dirty fixed fish tank Here I am starting to fill the tank with water, testing it for leaks. Fill it a few inches, wait, watch for damp spots, then add a few more inches and repeat.

using the python siphon filter to fill the aquarium I picked up a Python brand siphon a while back, and I love it. I use it for fresh fills on tanks, because a quick flick and it will suck the water out almost as fast as it can fill the tank. If you only go a few inches at a time, you can drain below the leak quickly enough to not get much water out of the tank as he holes are likely to be small at this point.

freshly rebuilt fish tank - no more leaksHere is the tank full. It is still in need of cleaning. This batch of water will get drained in a day or two. The fresh silicone seems to me to be hard on that first change of water. I will siphon the rest of the crud out of the tank while I am at it.



2 different types of light bulbs on the rebuilt aquarium Here are the lights. 2 different bulbs, one was flickering pretty badly. The new bulb is the left bulb. I think it’s a grow light bulb, not an aquarium bulb like the right one. Notice the difference in brightness between old and new. Florescent tubes loose a lot of brightness over a six month period of use.

After a couple of hours, it’s still holding water OK – no leaks. That water stinks though. Going to have to drain it to get that stank out of the tank.

The stand leans a bit forward as well, so I will need to shim it back about an eighth of an inch so the water is level. Not sure if it’s the floor, the stand, or what.

I am going to cycle this tank next week with some platys that I have for a couple of months, then move the Jack Dempsey into it, freeing up the living room tank for fish that don’t hide all day long.

So, what do you think?.

3 Replies to “45 gallon aquarium rebuild”

  1. Well, there is a lot of discussion about that. To the best of my knowlege, DOW is the only one who markets aquarium silicone.

    There are 2 major types of silicone curing agents, an acetone based one, and another one that I don't remember.

    The discussions I have read said not to get the ones with the 'bioblock' or whatever it's called anti-mold stuff.

    My gut feeling is that aquarium silicone is FDA food safe silicone repackaged.

  2. All that being said, I do build tanks with 'standard' silicone. Actually, the stuff I built my TV tank was expired automotive windshield silicone. It seemed to work just fine.

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