[edd]

  :)how long will 25 litres of resin last approximately with an ro machine

[Extremeclean]

It all depends on what the TDS reading goin into the DI is after the RO.

I have found the following equation to be really quite accurate.

This is based on a 25ltr bag of resin.

Divide 500000 by the TDS into the resin and it gives you how many litres of pure you should get out.

EG  500000 divided by 10TDS will give you 50000 ltrs of pure.

[edd]

thanks mate my tds is about 005 from ro  use about 500 litres daily so 9 months ish then