High Density Polyethelene

Reefdad68 · Jan 13, 2016

Is HDP Polyethelene safe for use in reef aquaria? Is there any concern for chemical emission causing issues with water chemistry?

143MPCo · Jan 13, 2016

Plastics that come in contact with your food or drink ‘should’ be safe based on the following general information. Look for the Recycle symbol (often on the bottom of the container) and read the number located inside the symbol.

The following list cross-references the recycle number (recycling symbol) with what is generally considered safe for food (or not safe).

Plastics Generally Considered Safe for Food and Drink

#2 HDPE (high density polyethylene) *see note below
#4 LDPE (low density polyethylene)
#5 PP (polypropylene)

Plastic Water Bottle or Soft Drink Container

#1 PETE (polyethylene terephthalate) typical water, soda, and juice bottles, not designed for reuse or storage due to the possibility of bacterial buildup, be sure to properly clean them if reusing. Varying reports regarding the possibility of BPA leaching over time.

Risky Plastics Not Safe for Food and Drink
These may leach or have hazardous ingredients.

#3 PVC (polyvinyl chloride) carcinogens during manufacture and incineration
#6 PS (polystyrene) possible carcinogen
#7 other (usually polycarbonate, sometimes labeled PC) may leach BPA (Bisphenol-A)

*Notes

All food grade buckets are made of HDPE #2 (high density polyethylene),
but not all HDPE #2 buckets are food grade.

Buckets that are not food grade may out-gas and leach into the container, as well as into the contents held within the container.

HDPE #2 buckets that are not food grade may have been manufactured with a non-food-grade “mold release agent”.

Randy Holmes-Farley · Jan 13, 2016

What application are we talking about?

Polyethylene itself is fine for most uses, but can't take heat.

Reefdad68 · Jan 13, 2016

I was thinking of taking a sheet of black HDP Polyethelene to use as back drop for my new 300 gallon tank and then mounting rock work to it. I also was considering using it for baffles in my sump. Thought?

Randy Holmes-Farley · Jan 13, 2016

It is hard to attach things to polyethylene with glue, but otherwise I think it would be OK in the water.

Wash it well with warm soap and water, then rinse very well.