Ideally your regulator wants to be for C02 so that they can cope with the 52 bar input pressure, they probably are if they came with Hydra. If they are 16bar regs then this is the max pressure they will do, they should regulate down to 10 bar.

Technobots do a 10-16 bar adjustable LP relief valve (but there is no problem using a 11bar one on 10 bar, it is going to blow if your reg fails which is what it is there for).