What goes first? Purigen or Chemi-pure?

[Lavey29]

Is the reason Boyd states not to run purigen with chemipure because they are very similar products that are synthesized to produce essentially the same tank results?

 

[Randy Holmes-Farley]

Boyd is not a very reliable source of info (see the above claims as an example) but where do they say this?

 

[schooncw]

Is the reason Boyd states not to run purigen with chemipure because they are very similar products that are synthesized to produce essentially the same tank results?

I don't think this is stated anywhere on the product!