How to Safely Clean a Secondhand Fish Tank or Aquarium

With all the warnings out there, one could quite easily be reduced to a quivering mass of confusion—but, never fear, you have come to the right place. You can safely and effectively clean a fish tank using natural, aquarium-safe, and cheap substances that you can find at almost any grocery/food store.

Replace or Reuse

The first major decision should be what you will reuse that came with the tank (assuming it was more than just the glass tank, such as substrate, decorations, or even equipment like filters, heaters, powerheads, and more) and what you should replace. Many times, the equipment that came with the tank may be damaged, broken, or so old that it doesn't make much sense to keep using (such as the case of those with filters that are no longer manufactured. heaters that may have some water leaking into them, or those canister filters that tend to leak once the o-ring seal hasn't been exposed to water in a long time).

Ideally, you want to check for the following when coming up with the game plan on what you need to replace, and what can you reuse;

1. Is the equipment that you are going to reuse in good condition (i.e. does it run correctly and not make any odd noises)?
   1. If it does make some noises, is it easy to repair (could you buy an impeller for the filter, or a replacement motor from the original manufacturer or online through Amazon/eBay easily)?
2. Does the substrate or decorations need any deep cleaning? Is there any paint that is peeling, or is there any growth (algae, dead plants, etc.) or hardwater stains that are on it?
3. Can you replace the item easily with a newer version, or does the piece fit what you are planning to do with the tank (in terms of not only theming/styling, but also what inhabitants you plan to keep within)?

Cleaning Supplies Required

To now clean the tank, and any of the decorations and equipment you plan to keep and reuse, you'll need the purchase the following to remove any possible diseases that can be sleeping or be stored within (such as Ich):

• White Vinegar (ideally a large bottle)
• 1 new bucket (one that has never been used with any household chemicals)
• Approved scrubbing pads (be careful if your tank is acrylic, as these are very prone to getting scratched very easily - something such as the original magic erasers or those sponges that have a rough side and a soft side for dishes work extremely well)
• Razor blade (if there are deep hard water stains all over the tank that won't get removed using the other cleaning supplies)
• Hydrogen Peroxide (any % works, ideally 2 bottles is more than enough)

You're going to need to have a set of cleaning equipment that is only ever used for tanks, as any small trace of bleach or other household cleaning supply can cause parameters in the tank to be out of wack or for any of the inhabitants to die over time as they are exposed to these.

How to Clean the Tank

1. Take all of the decorations, equipment, and substrate, and rinse these and the tank completely (ideally, outside to make it easier to pour).
2. Take some white vinegar and pour it on the equipment, and within the tank.
3. Use the sponge you purchased and scrub with the rough side on the outside of the equipment (and inside, for items like hang-on-back filters or canister filters), and also make sure to scrub the tank on all glass sides (being careful of the silicone seals for glass tanks, and being careful to use the soft side only on acrylic tanks).
   1. For Tanks & Equipment: Rinse the tank and equipment out with water completely until there is no debris or buildup left (if you have deep hard water stains, using more white vinegar and scrubbing will slowly remove it. If not, you can use the razor blade edge and slowly go against the areas with the hard water stains to lift the layers of calcium and limestone to remove until the white vinegar dissolves the rest).
   2. For Substrate: Make sure that you completely rinse the substrate with water running within the bucket until the water coming out from the bottom of the bucket is clean and has no debris or discoloration. You may need to turn the water flow slowly if using sand, and if using gravel it may need to be at a faster rate. Using your hand, slowly mix the substrate to make sure it's completely clean).
   3. For Driftwood: You can either clean this off using some hydrogen peroxide OR you can try to boil the driftwood in a steel pan that hasn't been used for anything else (and won't be after this, due to some staining that may occur on the pan).
   4. For Lace Rock/Other Rocks: In the next steps, I would place the rocks into the tank while you check for leaks and allow for the hydrogen peroxide to soak into it over the 24 hours to clean them and take anything that may be toxic or that is stored within, out.

After Cleaning

Once you have completely cleaned everything, make sure to place the equipment back together, using new filter media and filter pads to not add in any chance of there being any diseases that are on the older media and pads. If you haven't already, now is the time to make sure that you fill the tank up with water outside to check for any leaks, verify that the silicone layers are thick enough (and replace/reseal if required), and also clean out the equipment and verify it all works correctly.

After you have the tank is filled up, pour 1 bottle of hydrogen peroxide into the tank and have the filter(s) run for 24 hours. You may see bubbles appear in random sections, and this is normal as the hydrogen peroxide is cleaning those areas (or cleaning the intake/outlets of any filter(s) running). This is also the time to check that you are not getting any shock when placing your hand in the water with the equipment running, as there are cases where there is an internal short within a heater or filter that can cause electricity to flow into the water (and effectively shocking any inhabitants).

When 24 hours have passed of the tank being filled up, and the equipment running without any issues, you are good to empty the tank and place it inside where it'll stay to enjoy for years to come. Make sure to empty the filter(s) out, place it in the new filter media and pad(s), and add in any new substrate and decorations that you want. If this is your first tank, please make sure to complete The Nitrogen Cycle first before buying any inhabitants!