When to change RO/DI Filters

**R. Deschain** · 03-16-2008, 05:01 PM

Hello,

Haven't posted in a while, just had a quick question.

The TDS of my RO/DI water just went from 0 to 1. I realize I probably don't need to change anything yet, but when should I change the filters? (BTW, the TDS from the RO, before the DI filter is 12)

Thanks

**Phurst** · 03-16-2008, 05:16 PM

I prefer 0 of course, but I understand anything below 10 shouldn't be a problem.

**PhotoJohn** · 03-16-2008, 06:49 PM

the general rule is 10ppm but i would switch at 5 if i could afford it

***lReef lKeeper*** · 03-16-2008, 07:03 PM

i agree, i change out at 10 also.

**JustDavidP** · 03-18-2008, 11:33 AM

I change mine when they look like this:

Seriously, I change them, after backflushing and testing again, if the TDS is 5 or more.

Dave

**CarmieJo** · 03-18-2008, 10:54 PM

Hi James,

It looks like your question has been answered. I want to know, how's the tank doing? I'd love to see some new pix please!

**poppin_fresh** · 03-19-2008, 10:42 PM

James,
whats the TDS of the water out of the tap?? What GPD unit do you have?

The fact that you have a TDS of 12 after the membrane may or may not be ok depending on the membrane and your source waters TDS. If your prefilters are shot, resulting in the higher higher post RO number, it will deplete the DI resin faster.