How to clean a garage found tank

[Tanked]

I recently acquired a 5 gallon aquarium that had been forgotten in the back of a neighbors garage.  It has now been sitting for over a week without leaking so the seals are good.

The problem is how to remove whatever is growing on or possibly under the silicone.  A few drops of bleach in the water hasn't helped and the toothbrush has no noticeable effect.  I would like to avoid resealing as a first option. 

[Odd Duck]

On 11/2/2021 at 9:23 AM, Tanked said:

I recently acquired a 5 gallon aquarium that had been forgotten in the back of a neighbors garage.  It has now been sitting for over a week without leaking so the seals are good.

The problem is how to remove whatever is growing on or possibly under the silicone.  A few drops of bleach in the water hasn't helped and the toothbrush has no noticeable effect.  I would like to avoid resealing as a first option. 

You can add quite a bit of bleach without worrying about residual.  First, it rinses clean well, especially with copious rinsing (garden hose is my favorite but shower head on a hose works too depending on the size of the tank and a 5 is easy peasy.  I would rinse, then scrub again and see if that helps.  You can also use baking soda with your toothbrush to scrub.  Try magic erasers if you haven’t already.

If you decide to use stronger bleach - up to 1/4 cup per gallon of regular (not splashless, it needs more since it’s less concentrated) bleach, then after rinsing/scrubbing, refill the tank with tap water and let it sit with about 5 times normal dose of dechlorinator for at least an hour.

If all this doesn’t clear the icky from the silicone, you’re better off scraping and resealing.  Some would tell you that an old tank should be resealed anyway.  I’ve done both and had minimal leaks and not really any difference either way.  But I’ve never resealed a really big tank (not that it matters for a little 5 G).  Biggest I’ve done is a 70 G.

[Tanked]

On 11/2/2021 at 11:01 AM, Odd Duck said:

You can add quite a bit of bleach without worrying about residual.  First, it rinses clean well, especially with copious rinsing (garden hose is my favorite but shower head on a hose works too depending on the size of the tank and a 5 is easy peasy.  I would rinse, then scrub again and see if that helps.  You can also use baking soda with your toothbrush to scrub.  Try magic erasers if you haven’t already.

If you decide to use stronger bleach - up to 1/4 cup per gallon of regular (not splashless, it needs more since it’s less concentrated) bleach, then after rinsing/scrubbing, refill the tank with tap water and let it sit with about 5 times normal dose of dechlorinator for at least an hour.

If all this doesn’t clear the icky from the silicone, you’re better off scraping and resealing.  Some would tell you that an old tank should be resealed anyway.  I’ve done both and had minimal leaks and not really any difference either way.  But I’ve never resealed a really big tank (not that it matters for a little 5 G).  Biggest I’ve done is a 70 G.

Bleach was my first choice for the best route to take. Baking soda never occurred to me. If it comes to resealing, this will be the right one to learn on. 

[mynameisnobody]

I second the baking soda method, I’ve done it to clean glass lids that are completely covered in crusted, old algae and it comes off like a breeze. Good luck! 

[Tanked]

Bleach and baking soda were a both fails.  The toothbrush was actually lifting the feathered edges.  The tank is still watertight, but suspect.  I now have 2 new options: reseal it or make it a basement tank for some of the pond plants.

[Biotope Biologist]

I'd lean towards resealing as discoloration of silicone is a tell tale sign that it'll likely fail in the future, especially since the cleaning methods haven't worked I'd imagine it's the silicone itself that discolored.

 

Although as far as free tanks go, making it possibly an overwinter tank for pond plants might be your best strategy

[lefty o]

if the edges of the silicone are lifting from the glass, its done for. time to reseal or get rid of it.

[Odd Duck]

On 11/6/2021 at 8:29 AM, Tanked said:

Bleach and baking soda were a both fails.  The toothbrush was actually lifting the feathered edges.  The tank is still watertight, but suspect.  I now have 2 new options: reseal it or make it a basement tank for some of the pond plants.

I think you’re in for a reseal.  Better safe than sorry.