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Discussion Starter · #1 · (Edited)
I am trying to figure out what's going on with my water and am doing a little head scratching, hoping that someone can chime in and lend another perspective.

I can't locate my test results from last year when I did my first testing, I swear my RODI PH was around 5. So, I went ahead and tested my water again just before posting and about 4 times prior over the last few weeks and have come up with the following results. The water in our home is ground~well water, it runs through a water softener, Potassium Chloride is used to soften the water. That said here are my test results using various probing tools and API testing reagent. The probes are new and clean.

I thought my RODI water would have a lower TDS, I am pretty sure the TDS was less than 10ppm last year and my PH was a lot lower.
I always make sure to flush it and I have purged and cleaned out the 32 Gallon RubberMaid, Brute, trash can that I use to store my RODI water. The RODI water always sits for several days before I use it.

Test Results:
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Water before it gets to the water softener
TDS 353
PH 8.0 from Probes API reagent 7.5
GH 13
KH 13
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Tap Water softened by Potassium Chloride
TDS 438
PH 8.2 APRI Reagent 8.0
GH 3
KH 16
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RODI water that has been through the water softener
TDS 288
PH 8.0 from Probes API reagent 8.2
GH 10
KH 13
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What? Water after RODI is kh 13? That's degrees or ppm?

Your right, those readings don't make sense

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My RO water is 8 TDS, fluctuates around 6.5 to 6.8 pH when I test just RO with a meter
 

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Discussion Starter · #5 · (Edited)
I replaced the RO membrane about a month ago. I also used all the water in my reservoir, washed it out thoroughly. I replaced the Carbon and the Sediment cartridges about two months ago. I made the sure plumbing is set up correctly, it's actually pretty straight forward. The unit is an RO Buddie (RODI).

The two options I'm considering at this point are:
1. Replacing the two cartridges, see how that goes. Note any changes in water parameters. If need be, change the membrane. This is way (although I'm wasting water) I have a firm grasp on my variables and can swiftly figure out what's fouling up my RODI water system.

2. Just replace everything in one fell swoop, flush 30 gallons of water through the system into my garden outside and then start the RODI system back up and be done with the shenanigans.
 

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Ro/Di water TDS should be 0. I have color change Di resin whenever it turn yellow or TDS 2 it time to change. Ro membranes change out every 2 years. To keep Di resin from exhaust too fast I make more then 40 gallons at a time
 

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Discussion Starter · #7 · (Edited)
I now have two new cartridges for Sediment & Carbon replacements and a third for Resin and I also have a new membrane, basically an entirely new RO Buddie system rated at 100GPD. I have yet to replace "anything" and that's where I am a little unsure. What would you do at this point, if you were me?

If we were to tear into this a step further.

I have the option to either replace each cartridge, one at a time and see how that helps, or just the carbon and sediment or all three cartridges "resin" included.

It seems premature to change the membrane since it's hardly 2 months old. However... since I'm working on this tonight, after work and I'm eager to get my RO water back down below 6 PH and my TDS below 10, I appreciate any feedback.

I think one of my next posts is going to be about going with another RO system if I already need to change this membrane out. I'd certainly lose a whole lot of confidence if these cartridges turn out to be a bunch of cheap garbage that is hardly good for but a few hundred gallons of RODI water.
 

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The problem has to lie with your membrane, as that stage eliminates ~93% of TDS. Perhaps it was not installed correctly, or there is a tear/leak in the membrane? How quickly does your RO water replenish? If it replenishes quickly, then there must be a tear/leak.
 

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The problem has to lie with your membrane, as that stage eliminates ~93% of TDS. Perhaps it was not installed correctly, or there is a tear/leak in the membrane? How quickly does your RO water replenish? If it replenishes quickly, then there must be a tear/leak
YEs your RO membrane may now be leaking. Or one or more of the o-rings seals it has has failed. Check this o-rings for damage or deterioration. Also make sure there is no dirt or debris on the o-rings. A leaking Oring can cause high GH KH water to contaminate your product RO water. Also look at other tings in the RO unit for problems Leaks, plugged hoses or anything that doesn't look right.

Most people assume that any minerals the RO membrane filter out are flushed down the drain in the waste water stream. However some minerals do remain trapped in the membrane such as iron, calcium or other minerals. This build up of minerals in the filter may plug up the filter and result in slow RO water production. Or it may cause the membrane to tear. When the membrane tears all the minerals inside it are released into the RO water stream and that may increase GH KH and TDS to increase to a level above the source water. In your case the source water is the water from your water softener.
 

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Discussion Starter · #10 ·
Thanks to those that responded. I replaced the membrane and the resin cartridge as it was depleted and I am now at 0 TDS once again. Hoorah! Now I can focus on my ferts! Lesson learned.


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Discussion Starter · #11 ·
40Gallons of H2O filtered with the new Membrane and Resin cartridge and my PH is 6.5 which I am happy with. Should it be lower using the RODI system or is this an acceptable PH?
Thanks,
DD
 

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Discussion Starter · #12 ·
I just finished a bunch of tests using API reagents and an OAKTON ecoTestr pH2+ probe and figured I'd share, perhaps it will help someone else out?
RODI now producing H2O with the following parameters

Test Results from Jan 18,2020 after replacing RODI water membrane and Resin cartridge:
GH 0
KH 0
PH 6.4 from API reagent
PH from monitoring Probe 6.3
TDS 0 PPM
 

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Test Results from Jan 18,2020 after replacing RODI water membrane and Resin cartridge:
GH 0
KH 0
PH 6.4 from API reagent
PH from monitoring Probe 6.3
TDS 0 PPM
Should it be lower using the RODI system or is this an acceptable PH?
The water looks good. PH can get lower depending on how much CO2 is dissolved int the water.
 

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Agreed. With my own RO/DI unit, the API test kit is worthless since the pH is off of the scale acidic. I just purchased an electronic pH pen, so I will try to remember to update here after I test.
 

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Although it looks like it's doing a good job here, liquid pH test kits are unreliable as you approach 0 dKh. pH probes are better. I can dig up a link or 2 if anyone is interested.

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