Whilst working away yesterday I had a thought of how to test all the brands of resins out there.
This may settle the old "which resin lasts the longest"
Using an inline water meter to measure how much has passed thru a small 5 litre dumpy di vessel with an inline di vessel on the outlet side of the vessel I could measure several brands back to back ... all recorded for youtube.
The test would end the second the tds hits 001.
The brands I can think of are
Tulson 115 (the one I use)
Ionics
Puralite
Any more please add in a comment.
If run say 3 times a year then this would even out the old "must have been a bad batch"
Comments and thoughts please.

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List of contenders so far.
Tulson 115 (the one I use)
Ionics
Puralite
Dowex
Unger
indion
mag mb ( from gaps water)