I've been using the Arista RA-4 chemical kit from FreestylePhoto. I'm almost done with the developer, but still have a good amount of the blix. The only Arista chemicals I can find on the internet are in the full chemical kit, and I can't buy the developer individually. Would buying another brand of ra-4 developer be compatible with the Arista chemicals, or do I need to bite the bullet and invest in a whole new brand altogether?