Aquarium Safe Plastics

When I was gathering various tubs and containers to use in my aquarium maintenance, I wondered what plastic containers would be suitable and safe to use.  I didn’t want a plastic container that would leach harmful chemicals into the water I was transferring.

The answer is simple and relates to those little recycle symbols on the bottom of plastic containers.

Decoding the Recycle Symbol for Aquarium Safe Plastics:

A plastic that is aquarium-safe will also be food-safe. This is to say, the best containers to safely store foods are the best to use for your aquarium maintenance needs.

The little recycle symbol (three arrows formed into a triangle with a number in the center) helps recycle centers to identify resin plastics of like kind.  The best type of plastic for use with foods have the number 2 in the center.  These are plastics made of high-density polyethylene (HDPE).  Compared to other types of plastics that are categorized (numbers 1 through 7), HDPE is relatively stable and inert.  This means that it doesn’t leach chemicals into food or fluids over time.  This makes HDPE plastics with the #2 recycle symbol aquarium safe. From what I see, #2 plastics tend to be used for items with more strength and stiffness.

A close second to #2 plastics are #4 and #5 plastics.  #4 plastics are Low-Density Polyethylene, or LDPE.  #5 plastics are Polypropylene.  Polypropylene plastics have a high tolerance to heat, so many microwavable containers are made of polypropylene.

The only food-grade plastic I would avoid for aquarium use are #1 plastics.  These are PETE or PET plastics, often used for one-time items like plastic water bottles.  These plastics are slightly more unstable and can readily leach chemicals if used over time.

aquarium safe plastic made of #5

I’d prefer seeing the #2 or #5 symbols for items I was using for an aquarium.  My large Home Depot bucket is a #2 plastic.  The remainder of the small Rubbermaid or Tupperware containers that I use with the aquarium are #5 Polypropylene.

#2 plastic bucket that is food and aquarium safe

Best Practices for Cleaning Aquarium Plastics:

I want to mention that beyond the type of plastic you use for aquarium maintenance, it’s important not to contaminate aquarium containers with soap.

I never use any soap on my aquarium buckets and maintenance Tupperware.  Even new items purchased from the store, I only rinse with water to get them clean.  If you use soap, you risk contaminating your tank – soap and your fish/inverts do not mix.

Even the best aquarium-safe plastics can be ruined if you wash them with soaps, so avoid that temptation – only rinse with water.

12 thoughts on “Aquarium Safe Plastics

  1. From what I’ve gathered in an article written around 2 years after this one, #2 is more likely to leach estrogenic chemicals than #5, as is #4, so I would’ve listed #5 as the best option out there.

    1. Thanks for the link. I’ll have to put some thought into this. Certainly estrogenic chemicals pose health concerns for human consumption – not sure how these concerns rank when compared to the top needs of aquarist.

  2. I am moving house and want to take my goldfish with me that at the m oment are in a large pond…
    they need to stay in a large container whilst a pond is being built…which could take a month say.
    Can I use a plastic dustbin which will give them depth and keep them safe?

    1. The type of container isn’t your main concern in this scenario. For a move, make sure the container is structurally sound to hold the weight of the water.

Leave a Reply

Your email address will not be published. Required fields are marked *