should i change my filters on my RO/DI unit?

[disaster999]

its been around a 9 months to a year...dont quite remember...since i last changed my DI and carbon filter. I lost my TDS pen so i couldnt check my water for a while. after finding some really cheap filters and TDS pen from china, i ordered them and tested my water. to my surprise the RO/DI water still reads zero.

 

should i change them out or wait till im getting 1-2 PPM TDS?

[MitchReef]

My prefilters are going on 2 years now, still making good water. I flush my membrane for like 5 or 10 minutes every time I start it up.

[AZDesertRat]

The prefilter and carbon block should be changed every 6 months like clockwork regardless of the amount of water you have made. They are there to protect the RO membrane and have very little to absolutely no effect on final TDS so a TDS meter will not tell you their condition. They remove TSS or suspended solids, silt, particulates etc and chlorine not TDS or dissolved solids, the size difference is like 0.1 ppm for suspended solids and 0.0001 for dissolved solids which is where the membrane and DI come in.

 

Another method is to use a pressure gauge to monitor pressure drop across the filter array and a low range chlorine test kit to monitor for chlorine breakthru but the 6 month method is much easier and safer.

 

To troubleshoot a RO/DI system you need 3 TDS readings. Tap water TDS, RO only TDS and RO/DI TDS.

The Tap and RO only tell you the rejection rate or removal efficiency of the RO membrane which is the workhorse and the RO/DI TDS tells you the condition of the resin.

 

Always remember to disinfect the system while you have it down for filter replacements, it takes about 5 minutes and could be a life saver.

 

Flushing membranes is a "feel good" or "warm fuzzy feeling". It has no proven value or benefit and frankly is a waste of time. Make sure your waste ratio is set at 4:1 and thats all the flushing required.

[disaster999]

Thanks AZ.