At what TDS reading=change filters?

[purplereef]

Hi Guys,
Just wondering when everybody will change there RO filters, at what TDS meter reading? I am wondering if there isn't something sneaking through my filter that is fueling my Cyano problem. Thanks, Dan.

 

[8BALL_99]

uhh your TDS should be Zero on your output of your RO/DI.. The TDS of just the RO depends on your input water. Depending on your RO membrane they are 95-98% rejection rate give or take.. So say if your input TDS is 140 your output from your RO only would run anywhere from 5 to 12. Again give or take. If your input TDS stays about the same your output TDS starts going up then its probably time to change the membrane

Now all that said if your talking about your prefilters then you should change them every 6 months is the general rule. Really time has nothing to do with it. Its a matter of how much water you use. Your prefilters won't really effect your TDS inless you wait to long and your membrane gets nuked. I have Clear housings on my Prefilters. I have a rough Idea of how much water I use between that and what the first filter looks like is what I go off of.