I admire you guys for giving it a go, but far too dangerous for my liking, have enough fun throwing hypo and ammonia together

I agree with Daz if your tds is higher the ro will knock it down, mine goes from low 300's to 5 - make 10k of pure per week, double di and not changed resin in 12 weeks.
I'd rather window clean for those 3 hours with less risk to health and I could buy 2 bags of resin.
That's just my perspective on it, btw happy to save spent resin if anyone wants to collect it
Darran