Stupid pinhole leak!

[KreativJustin]

So I bought a used 75 gallon, used but looked in good shape. I filled it with water and noticed on the back left side that the tank had a TINY pinhole leak. So I marked it and drained it down below that point and it is holding water below that point. Now on the inside of the aquarium, the bottom sealant is large and looks great, however, on the corners the sealant is very thin. I really do not want to reseal the bottom of the tank as well and just want to do the sides. Is it possible to seal the corners and leave the bottom of the tank alone, and if so, does anyone have any advice on not making a new leak point from removing the old seal and putting in the new one?

[Colin_T]

Can you post a clear picture of the tank where the leak is?

Check the silicon for colour and texture. If the silicon is cream or white, or has bubbles in, or is hard, then it's failing.

Good silicon should be pale blue or almost clear or black (if it's black silicon). It should be firm but slightly squishy and not hard or brittle.

You can use a single sided razor blade or a sharp knife to trim the old silicon away from the inside of the tank. Then smear a layer of new silicon over it. You don't cut into the silicon that is between the glass, just trim up the piece on the inside that you can feel.

If you can see a big hole in the silicon between the glass, you can squirt a bit of silicon between the glass and then smear some over the inside and outside.

Use your finger to wipe along the inside of the glass to smooth out the silicon. Then wipe the silicon off your finger onto a piece of newspaper or paper towel.

*NB* Do not inhale the fumes when using silicon because you can pass out.
Make sure there is plenty of air flow around the tank when you glue it.

[KreativJustin]

I am at work now, if I remember tonight I will take a picture, I still have to drain out the remaining water. The bottom seal looks really good, the inside corners do not have very much seal at all from what I recollect from last night. I just asked the guy if it held water when I bought it, and he said it did the last time he had it up, but he never did say when he shut it down - so he may not have known. I didn't notice that the corner seals were not as good as the bottom when I bought it.

[KreativJustin]

I took pictures, it was kinda hard to get good ones. The area where it is leaking, there is barely any silicone on the inside. I feel so dumb right now for not even looking when I bought this thing.

I've attached the pictures.

[Colin_T]

If the creamy patches are between the 2 pieces of glass, the silicon should be replaced if it covers more than a couple of inches.

You could patch it if that is the only dodgy silicon on the entire tank, but if there are other patches, then it might be worth removing the glass and resealing it. This usually entails getting a single sided razorblade and cutting the silicon all around that sheet of glass and carefully removing the glass. Scraping all the old silicon off and then reapplying new silicon. The glass is usually taped to the tank while the silicon dries.

[KreativJustin]

Thanks for your help Colin. I am actually going to call it a loss on this aquarium, my local aquatics and exotic pet store offered me $50 on store credit. I can also try to get $100 OBO out of it on facebook marketplace as a reptile tank. I have a lead on a 75 gal aquarium (tank only), I am just refusing to buy anything unless its full of water when I get there. Plus the seals looked good from the pictures I seen. Worse case scenario, I will buy a new Marineland one, at least they will have a warranty. I'm already invested, so I'm not backing out now lol.

--edit-- the creamy look was between all of the glass, I showed my wife what our 20gallon silicon looks like between the glass and you can tell the difference. The 75 looks hard, not soft like the 20g.

[m.j.gomez]

Originally Posted by KreativJustin

Thanks for your help Colin. I am actually going to call it a loss on this aquarium, my local aquatics and exotic pet store offered me $50 on store credit. I can also try to get $100 OBO out of it on facebook marketplace as a reptile tank. I have a lead on a 75 gal aquarium (tank only), I am just refusing to buy anything unless its full of water when I get there. Plus the seals looked good from the pictures I seen. Worse case scenario, I will buy a new Marineland one, at least they will have a warranty. I'm already invested, so I'm not backing out now lol.

--edit-- the creamy look was between all of the glass, I showed my wife what our 20gallon silicon looks like between the glass and you can tell the difference. The 75 looks hard, not soft like the 20g.

Hello, resealing a tank is very easy. Here is a link that shows how.
I usually do all my 2nd hand tanks & it will only take a few hrs of your time at minimal expense. Also if you plan on being in hobby for a long period of time good skill set to have. Hopefully this helps!!!!!

[KreativJustin]

Took the old tank down to the lfs and got store credit, bought a new marineland 75. Holding water so far. + painted the brown stand that came with the leaky tank.

As you can see I do not that hose lol, going to hard plumb soon.