I was also told to steer clear of pressure treated. I will look into CPESDo not use treated wood- resin does not adhere well. Douglas fir is a common used wood probably what was originally used. Pretreat the wood with CPES-https://www.rotdoctor.com/products/cpes.html until it wont take anymore,it is compatible with epoxy resins. US Composites, https://www.uscomposites.com/ has epoxy at more reasonable prices.