Not used RO for 12 days so gave it a flush for 10 mins then adjusted waste valve and took pure water hose off DI for a few mins. This is a tremendous tip that I'd never heard of before(until a few weeks ago).
Tap TDS 181
After RO 008
After RO for the first couple of mins it was reading 082!
After RO and DI 000
This little tip alone will save a resin change over the course of a year for sure!
I used to think this would save resin & I still use this method although I have JG tee pieces & taps to divert rather than disconnect hoses.
I do think however, that in my case & in the grand scheme of filling a 1000 litre ibc tank for six hours or so, that 60 to 90 seconds of high tds isn't going to make much difference. But like I say, I do still use that method unless I'm on holiday, in which case the RO is left switched on permanent with it's auto cut off booster & float valve as I wouldn't trust my employee with it as he knows nothing about pure water production.