the way I do it is .... The water comes out of my outside tap , it goes through two Di vessels and then into 25 litre barrels as I use a back pack system , The resin I use ( the only one up to now) is Unger. Defo got the vessels in the correct line . I filled 5 x 25 litre barrels ( which read 000ppm) and then I tested the first vessel which read 105 so it had been working for about an hour as I have the water running as slowly as poss
My tap TDS is the same as yours & I get at least 11,000ltrs of pure per vessel change (10 ltrs of resin)
Something is wrong, that's for sure. This is my advice-
First make sure that both vessels are installed & working correctly i.e. are the riser tubes fully inserted in to the head unit past the sealing "o" ring?
Now, I don't know at what stage you have introduced the "second" vessel but this is what to do-
If the vessels are installed & working correctly then remove the one reading 108ppm. Use just the one which is reading 000ppm. We'll call the removed (108ppm) vessel No-1 & the in-use (000ppm) vessel no-2.
So, when vessel 2 starts reading 003/004ppm you need to fill vessel 1 with fresh resin & add it back into the system. Now vessel 2 (003/004ppm) needs to be pre-filtering vessel 1 (fresh resin). The filtering line should now read tap>vessel 2>vessel 1>barrels. Keep this cycle going the same way from now on. My older resin vessel never reaches my tap water tds before the newer resin needs changing anyway- so mine would never get to 108ppm, it usually gets to about 50/60ppm when the newest resin gets to 002/003ppm & this is when I change.
Also, I would get some Tulsion MB115 resin. Unger are well known for rebadging other products with their own name & your resin sounds very like Purolite MB400 - which is crap!!
Hope that helps a little & you're are right to have a slow flow through the vessels, resin works much better that way.
