Monitor MZ 25C Freeze Protection

i've grown tired of the long, dark, cold winters up here in eastern Washington and want to become a snowbird in Arizona. I need to add freeze protection to my hydronic heating system so I can leave in the winters. I have a monitor MZ 25C boiler that is piped directly in the system. The owners manual describes a product called BIONIBGEL for freeze protection but I've been unable to find any suppliers for this product which aparently comes out of France.

The pex I installed in the floors is non-barrier. That's a mistake but one that can't be corrected. I am thinking I'd like to install a buffer tank to help with short cycling, and to isolate the boiler from the rest of the piping and use oxygen barrier pex for that part of the system. I will just run traditional glycol in the floor piping but I'm not sure what to run in the boiler/buffer tank. The heat exchanger in the boiler is stainless steel but the water jacket is aluminum. Can I just run an antifreez that is compatible with aluminum boilers? What's so special about BIONIBAL/ BIONIBGEL? Is there any place I can buy that stuff in the US? Is there something equivalent I can use? I don't want to destroy my boiler with bad circulating fluid and I don't want to purge the system every time I leave for the winter.

Aluminum safe glycol is not cheap, by the time I install a 50Gal buffer tank I'm looking at some serious money for the freeze protection. Thanks for any suggestions.