Crystal pro doesn't seem to last very long. But it could be due to the tap water in my area that has 165 ppm TDS reading. Right now, I'm getting 95ppm TDS reading from my crystal pro and that is only topping up ard 20 - 30L of water per week for 2 months.
Will be getting a portable RO unit from US soon to replace the Crystal Pro unit. This will last ard 2,500 gallons before the filters need replacement.
Also may ask the supplier to DIY a DI unit for me. First stage 5 micron Sediment Filter, 2nd Stage 5 micron GAC filter, 3rd stage 5 micron coconut carbon block filter, last 2 stages DI filter. Good thing about this unit is that all the filters including DI filters will be replaceable/refillable. So only need to get the bulk DI resin or individual filters when they need replacing.
Right now, using the Crystal Pro, I will have to replace all the filters every 2 months which is unacceptable.