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crs751
12/12/2011, 02:38 PM
Are you supposed to clean the probes on an in-line TDS meter? I an getting erratic readings from the meter after replacing the DI resin and wondered if the probes could be dirty. If you can clean them how is it accomplished? If they can't be cleaned can they be replaced?

Thefilterguys
12/13/2011, 08:25 AM
What are your erratic readings and what kind of tds meter do you have?

Jim

crs751
12/13/2011, 06:29 PM
The meter is an HM Digital DM1. Prior to replying to your post I opened the valve to my salt water holding tank and turned on the meter. The initial reading was 9ppm and jumped to 25ppm before settling back to 5ppm. This is the first I've noticed this type of behavior; the meter has performed flawlessly for the several years I've owned it. Thanks for your help.

Thefilterguys
12/13/2011, 08:21 PM
The jump in tds is called tds creep and is normal and happens every time you start up any membrane in the first minute of operation. I don't think anything is wrong and we don't recommend cleaning as you are measuring pure and ultra pure water. The 5 reading should be your normal performance reading unless it has been running at a lower number.

Funny how something that is normal operation suddenly catches our eye, Your normal and I hear lots of things like this everyday.

Happy reefing
Jim

crs751
12/14/2011, 07:35 AM
Thanks for your help Jim. One last question, at what level of ppm's should you change the DI resin? I usually change it when the levels hit 2ppm or so. Is 5ppm my new 0ppm level? I know when i change the DI the meter reads 0.

Thanks for your patience with these questions.

Thefilterguys
12/14/2011, 08:47 AM
You should always see zero tds from newly changed DI resin and we recommend changing at a reading of no higher then 2-3 at the highest. The 2-3 number allows leeway and any constant number (1) over zero is a change indicator. Once you see a reading DI resin starts shedding and throwing back what it has stripped. Both legs of the resin may not be exhausted yet, accounting for a lower then feed reading, but for all purposes the resin is exhausted.

Jim

crs751
12/15/2011, 10:23 AM
Thanks Jim. I'll get it changed out.