[WhiteRaven]

So I tested my RO water I got from the local grocery store and it tested at 4° kh straight from the container. I've only used this container for RO water. I rinsed the test tube a couple if times first in the RO (dumping rinse water out and not back into container) before testing.
Is this considered a normal possibility for RO water? It's not RO/DI water. Or is the store water not really RO water? Or am I somehow getting a false positive? Thoughts?
In either case 4 is my target (tap water here is very hard 14+ th and tests 9+kh, varies throughout the year). I mostly wonder if I can trust that the water I'm getting is truly 4kh for buffer and not a false positive from some other contaminate. I hope it is good because then I don't have to mess with baking soda and kh.

 

[livingword26]

Its probably just RO, not RODI. Even with a new membrane, many minerals are not removed without the DI resin, and their RO membrane may be worn out also.

 

[nel]

Even normal RO not RODI with working membrane MUST have KH=0, GH=0. So it's not real RO or the membrane is broken. You shouldn't be getting false positive, probably just worn out membrane.

 

[WhiteRaven]

Thanks. It makes my target parameters. I'll continue to use it for now and check the water parameters each time. I'm thinking I'll need to add dechlorinator to the water too then. I hadn't been because I was expecting it to be clean RO.

 

[Zorfox]

R/O removes 90-98% of these minerals. DI removes the rest. A KH of 4 degrees is darn high for R/O.

I had the same problem years ago. I was using water from a grocery store R/O machine. It had high GH and KH. I checked the inspection date and it was over two years expired! I told the manager and it was repaired. After that the numbers were within range. You may want to check the inspection sticker as well as alert the store manager.

 

[WhiteRaven]

Good thought. I checked the label on the unit It says every month the the company that maintains it checks the filters, UV light, tests water parameters, etc. The last day was may 3, 2016. I tested the water again, it tested at 3kh.

 

[bluesand]

yeah you should check the date on the machine. The RO water that i used to buy had a GH of 3. After the company moved to a new location, im getting KH/GH 0.

 

[WhiteRaven]

So I got RO water from a store in a neighbouring town on my way to work. It was same company that serves the water unit as the previous store. Its service date was within a few days of the other one, and I got the water a week later. The water from the new store tested at 0 kh.

 

[Rob in (ca)]

With your tap water at 14+ i would look into buying a RO system and just mix the two.