in the next couple of months i will be upgrading to a new system,at the moment i use the ionics pro2 trailer but will be getting a van system with a 650 lt tank,which one to buy?ionics is very good but i am finding there filters are running out too quick and at the moment it is costing about £150 a month and i only use 300 lts a day,water is 370 out of the tap,my business is expanding and if it comes to using 600 lts a day i do not want to spend £300 a month on resin,£3000+ a year,so i need help to pick a supplier whos system is cheaper to run,diy or off the shelf,cheers robert