OK, after testing my kit yesterday with a TDS of 010 and lots of rinsing, I still have spots

So looking at my current resin holder that probably only holds a few cup full's of resin I'm thinking of buying a proper bottle to connect to my RO system.
There's a few second hand one's on ebay but I could certainly use some advice on what resin to use, price, and what vessel to go for.
I did get my TDS down to 001 for a while when I tested it all and filled my holding tank, but it looks like that rose during filling and now I'm left with a tank at 010. The resin vessel on my RO system is so small I suspect it's useless
