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Discussion Starter · #1 ·
I just got home after being gone for a month and a half, and i was doing water changes as usual when all of a sudden i noticed a really high ph. After doing some checking i figured it was my RO unit. My waste water and RO water are running about 7.5, which usually my RO is running 6 or below. My membrane is a little over a year old, could this be the problem? I am getting a TDS of 0 also. My tap ph hasn't changed either.
 

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Discussion Starter · #3 ·
I hear 1-2 year and 3-5 years, so i'm not sure.
Another note i'm on well water, so it doesn't change much, and i haven't see a change with my testing.
 

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Discussion Starter · #5 ·
good to know, So wonder whats causing the sudden increase in ph? i've never had this problem. The DI is about have used and still producing 0 tds. I don't think is was CO2 in my water before because it would never rise after sitting a day or two.
 

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The useful life span of the membrane depends on source water mineral content and if a flush valve is used to surface clean from time to time. Prefilter maintenance schedule, volumes produced and several other factors so time really doesn't factor into it. I measure the product to reject ratio and when the volume shift (more reject, less product) I know it's starting to plug. If tested pH is rising I would not trust the TDS being 0.0ppm and would KH test the water.
 

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Discussion Starter · #7 ·
The useful life span of the membrane depends on source water mineral content and if a flush valve is used to surface clean from time to time. Prefilter maintenance schedule, volumes produced and several other factors so time really doesn't factor into it. I measure the product to reject ratio and when the volume shift (more reject, less product) I know it's starting to plug. If tested pH is rising I would not trust the TDS being 0.0ppm and would KH test the water.
I don't have a flush valve, and i'm pretty sure my mineral content is pretty high. I produce about 25-30g a week, or maybe 2. The product to waste are about the same and i just changed my prefilters a month and a half ago. KH is still 0, i just tested the storage tank.
 

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If you have faith in the TDS the only other thing I can think of is a lack of CO2 content and high O2.
My RO will bounce up slightly, 6.8 - 7.2pH in the holding tank with air on it the night before use.
Using chemical tests you could double the volume of the water sampled and that doubles down on the results value. I think you're justified in questioning the shifted pH value.

150 - 200g is the average RO made weekly here. 204 - 214TDS in and 1-2ppm out without DI use.
 

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Discussion Starter · #9 ·
Thanks for the help. I am trying to do a water change on my CRS and taiwan bees, but i prefer not to dump in that high of ph. I just checked the bucket and it was 8.3 and still 0 tds, so was my bucket of mixed water. Thats higher than my tap. I have a cup of tap water sitting out to see if it changes at all. Its just weird, something is going on.

My tap tds is about 320ppm, and with good resin will be 0ppm when done.

I've been using liquid test and my digital ph meter to verify everything, even checked it in 2 buffer solutions.
 

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Discussion Starter · #10 · (Edited)
Well come to some what of the conclusion that the di is removing something that once removed bumps my ph, because before the DI my ph is around 6.8. i walked back and the ph was lower than before, and i just threw in some air and its now dropping. So i guess I will air my water the night before use. Also my ph meter is on its last leg. Time to find another brand.
Thanks for all the help.
 
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