Looking to get into fishkeeping, but not sure whether you want to invest hundreds of dollars just yet? Or maybe you’re in need of your 18th tank upgrade and, as is common for aquarists, are running out of funds? Consider going thrifty and buying a used aquarium.
We don’t buy used for our clients here at FantaSEA Aquariums unless they want us to. For personal use, though, we love helping out the environment (not to mention our wallets!) by buying tanks and gear off other aquarists. We’ve become pretty good at finding deals, pre-purchase inspection, and post-purchase cleaning, so we’ve decided to put together this guide to help you do the same.
Why buy a used aquarium?
Yours truly is probably the biggest fan of shopping for used aquariums in the FantaSEA team. In fact, I think only one or two of the 15+ aquariums I’ve owned over the years were store-bought, and those were discounted.
Some of the biggest advantages of going secondhand include:
- Price: new aquariums and stands can be really quite pricey. Used set-ups, even those that are in great condition, usually sell for a fraction of the retail cost. You could a medium-sized or even large tank for the same price as a small one. This, as we’ve mentioned here on the blog, can be a great idea.
- Extras included: sellers are often willing to throw in all sorts of accessories you’d normally have to buy new. It’s not unusual to get the stand, filter, and/or other equipment for free.
- Immediate availability: retailers don’t always actually have their catalogue in stock. If you want to start your aquarium now, you can just go pick up a used one from its previous owner rather than waiting for a new one to be shipped.
- Environmentally friendly: give an old tank a new life and prevent a new one from having to be produced and shipped. One of my favorite things about thrifted tanks!
Socializing
As an added bonus, I also personally just enjoy going to pick up used aquariums. Sometimes it’s a simple handover, but on other occasions, I’ve been offered coffee, fish room tours, and hours of aquarium conversation.
I once picked up a tank from a guy who had a 15-ft Amazon biotope tank smack-dab in the middle of his living room. We chatted fish for ages before he helped load the immaculate 40-gallon breeder I bought off him (for about $70 with a big canister filter included) into my car. It’s nice to connect with other aquarists—they tend to be lovely people.
Tip: If you’re ultra-thrifty like me, you can even find fish tanks on the side of the road and next to bins. I braked hard for a 30-gallon breeder a few days before writing this—it needs a thorough cleaning, but it holds water like the day it rolled off the production line. I didn’t mind the $0 price tag, nor being able to save it from ending up in a landfill.
Pre-buy check: Questions to ask
If you regularly buy secondhand items off Facebook Marketplace, Mercari, Craigslist, and other platforms, you’ll know that you can find absolute gems. You’ll also know that it’s important to check over anything you buy before sealing the deal, and to ask the right questions.
Fish tanks that have been in storage for a long time can become leaky as a result of silicone degradation. Well-used aquariums can have scratches, pesky hard water stains, and salt build-up. Equipment may have stopped working properly or gone rusty, especially if it’s been sitting in a box for Poseidon knows how long.
Luckily, it’s not too difficult to avoid buying a cat in the sack. And as we’ll see in the next section, even if your brand-new old tank does turn out not to hold water or be covered in filth, that doesn’t mean you have to throw it out. Prevention is better than cure, though, so let’s have a look at what you should ask the seller before handing over your hard-earned dollars.
Inquire about the following:
- When was the tank last used? Has it held water recently? Less time in storage means less time for the silicone sealant to dry and crack.
- Has the equipment been tested? Heaters*, protein skimmers and the like should be submerged and turned on to see if they still work as they should, especially if they’ve been sitting in storage for a while.
- Were any custom adjustments made or DIY jobs performed on the tank or equipment? If so, what was done? Does everything come with all its original parts?
- Did the seller experience problems with the tank or any of the gear? Why are they selling the aquarium?
*Heaters are the riskiest aquarium equipment to buy secondhand, as they can fail in more dangerous ways than other accessories. I’ve done it, but only after thorough inspection. Or just buy yours new!
What you’re looking for
The ideal secondhand aquarium is owned by a fishkeeping enthusiast looking to sell it because they’re upgrading or have found themselves with too many tanks on their hands. It was only recently drained, ideally comes with recently used, high-quality equipment, and its owner can tell you all about its history.
Red flags, to me, include the owner not being willing to get into detail (unless it really is a steal or free, in which case I just zip it and take the tank before they change their mind) or saying everything works fine without proof. I’m also not a big fan of aquariums that come with fish, as they rarely match your ideas for your set-up and can be a hassle to rehome.
Remember rule #1 for buying anything secondhand: bring cash, but be ready to walk away.
Tip: Check for chips and scratches, as these can’t really be fixed in glass tanks (acrylic can often be buffed). If there are too many, even a good deal on the tank may not be worth it. It’s also a good idea to check the stand and lights—if they’re included—for water damage and warping.
Used aquarium clean-up
Unless you’ve run into a really nice seller, secondhand tanks often need some clean-up. Dried algae, hard water stains, leftover gravel bits, and other gunk are easy enough to remove. Even cracked and leaky silicone can be fixed, although that’s obviously a bit more work.
Here are the initial steps we take when we bring an old aquarium home:
- Place the aquarium outdoors or in the shower/tub. Fill it with water and leave it for about a week, regularly checking for leaks.
- All good? Drain 75% of the water and add vinegar (1:1 concentration). Scrub gunk with a soft sponge or old credit card. It should be softened after a week of being submerged.
- Struggling with the gunk? Drain the water and vinegar mixture and try again with warm water and a splash of bleach. ☣️ Never add both vinegar and bleach at once!
- Struggling with hard water stains? Drain and cover in a vinegar-soaked towel for an hour or so. The acidity dissolves calcium.
- Any gunk on the outside, like sticker or tape residue, can be removed with acetone; finish by wiping with glass cleaner.
- Rinse the tank thoroughly and you should be all set. Exciting!
Re-sealing
If your tank did leak, or if the silicone looks suspicious (flaky, cracked), a re-seal is in order. This warrants its own full guide, but it’s doable even if you’re not experienced. Basically, you remove the silicone that sticks out on the inside of the tank with a razor blade, leaving the bits that are between the panes alone so they don’t come loose.
After removing the degraded old material, you re-seal the whole thing with fresh aquarium silicone. Wait for about 72 hours before leak-testing again.
Congrats, you traded some elbow grease for big savings! Not sure what to do next? Have a look at our article series on Aquarium Set-Up to find out how to set up a new fresh or saltwater fish tank and make it ready for fish and invertebrates to live in.
Conclusion
Buying a used aquarium—or even picking one up from the side of the road—can save you a lot of money, especially if you’re willing to put in a little cleaning work. Perfect if you’re on a budget, want to be environmentally conscious, or just like more tank for your buck!
Dreaming of your own aquarium, but feel like going secondhand is too much of a hassle? It does take a little time and a good eye. For a maintenance-free fish tank, contact FantaSEA Aquariums instead: we’ll design, build, and even regularly clean it for you.
