I'll tell you how the company would respond. Its so predictable.

What is Hydrx? Propylene glycol. What other product is propylene glycol? Zerex, which is pretty much what Hydrx is anyway.

Is Ethylene Glycol an acceptable substitute? Probably. So is Pentosin alright? Yes, but the company wouldn't want to outright state that its alright because they want to sell you little bottles of Hydrx.

Then what is PT Nuke? A biocide that protects against algae. Does PT Nuke protect against corrosion ? No.

So, you failed to protect your loop against corrosion, and so its your fault.

This is not my argument on behalf of the company, but it would be the standard CYA response.