New DI cartridge, when?

[litlfishy]

I have a 4 stage Spectrapure RO/DI and currently have the silica-buster DI cartridge. Realistically, how many gallons of water can I run through it before it needs replaced. I am concerned about removing as much of the silicates as possible. I change my .5 micron sediment cartridge too frequently probably, and my carbon filter frequently as well just to be safe. Thanks for the help.

[The H2O Guru]

You need to divide the output of your membrane into the capacity of the D.I. cartridge .
Say your permeate ( R.O. ) water is twenty p.p.m. and the cartridge is rated at 6,800 p.p.m. When you divide 6,800 by 20 your answer is 340 gallons of water ,
Some cartridges are color changiing , others will require that you test the output TDS with your tds meter . If the TDS is staring to climb you should consider obtaining another cartridge .

the H2O Guru