What is the best water system sterilizer?

Good morning everyone....We're just about to prepare our water system for the coming season. In the past, we've used 'milton' & been very confident the water barrel & pipes have been sterilized ,although I must admit I've been a little concerned about the possibility of a 'corrosive' substance in the water tank, even though we flush the system through several times to clear the Milton after it's 'done it's work'. Now however, we've seen a 'u tube' video suggesting PURICLEAN is the best product for this job, because it seems it clears 'a film/slime' from the pipes,which Milton won't achieve.

My question is, "what do other caravan/motorhome owners use for their systems.?" Maybe this topic has already been discussed & I'm sorry for asking but I don't always use this discussion site but know I'll get good advice when I do...so I'd appreciate a response; we will then get a general idea of what is best and more importantly how often such a procedure is carried out. Thankyou.