RODI Help

Joshbrokeit

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I have spent awhile lurking around the forums. I wanted to see if I could get some recommendations for my RODI system and I haven't been able to find the answer to my question so I figured I would post and see if there is any advice. Thank you in advance.

I have two problems, poor RO performance and DI depletion. Doesn't seem to be CO2 relate - please read.

Well Water
Incoming TDS 75-90ppm (depending on the time of year)
RO output TDS 9-14ppm (depending on the time of year)
DI output TDS 0ppm
Depleted Resin (brown color) TDS 5ppm (steady, doesn't rise)
No Water Softener System (I do not have hard water)
68-70 degree water
lowish PH (6.6-6.8)
Booster pump I have tried everything from 50psi - 90psi normal incoming water pressure 40-50psi
Pre-filters 1micron and carbon

I am on my 3rd 75GPD membrane. The first BRS, the second spectrapure, the last Amazon DOW membrane (purchased new membrane housing).
550ml with flush (came with the original unit), spectrapure capillary restrictor (cut to 4:1), and Amazon 800ml flow restrictor (no difference in performance on flow restrictors)

I can take the RODI system off of my house and go to another house that is not on well water and get a solid 0-1tds coming through all membranes. I am at a loss as to why there is no way for me to get anywhere near advertised rates.

There was one time I made water shortly after having the well pump replaced that I was able to get good performance from the membrane (they shocked the well after pump install). Shortly after the chlorine smell went away in the water coming out of the tap I could make 0/1tds water out of the membrane. A week later it was back to roughly 9tds.

Any recommendations would be greatly appreciated.

Now onto the DI part. In about 80-100g my di is 'depleted' (5ppm). I have tested CO2 with kit and measured temp, alk, and ph. Same performance on brs resin, spectrapure (silicabuster/di combo), and amazon di resin
Temp - 70
Alk - .3
PH - 6.6

Most of the time my CO2 is between 0-1. Thinking that I must be testing something wrong I built a CO2 degassing chamber (3" 3' PVC, airstone) and also let a 44g can sit overnight with airstone. I am still measuring close to the same parameters, but my tds dropped 3-4tds (i understand not co2, just not sure what) through degassing chamber and when sitting in trash can. BUT DI resin is being depleted at the same rate. I would have expected some resin life extension if there was any problems with CO2.

I understand no one can 'guess' what is in my water. I am looking for recommended next steps, or recommended water test. I am considering an ICP test, but not sure if I should take an incoming RO water sample, or a leaving RO water sample

Currently leaving RO membrane
No measurable Phosphates
No measurable Nitrate

BRS suggested CO2 for resin depletion (right after I purchased the unit); did not note the poor performance on RO membrane (1-2yrs ago)
Spectrapure accepted the performance on the membrane; and I believe suggest CO2 issues for resin (6m-1yr ago)

I'm sick of buying water or worrying about the 9-14tds could be. I stop using the water after I hit 5ppm out of DI. I am working on a 150g aquarium build, so I am going to need access to good RO water source. I don't think spending $800 on resin a year is the best solution.

Greatly appreciate any help. Thanks!
 
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Joshbrokeit

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Thanks.

Yes I would, but I'm sure which one would be the best. Part of what I am trying to figure out is should I test well water coming out of the tap or after the ro unit. There are a lot of well water test and I am not sure which one would be the best. When they replaced the well pump I asked if they would test the water, but since they just shocked the well they said they would not recommend it. Most of what they were testing for was bacteria, ph, hardness, etc. the test didn't seem very thorough.
 

Doug6952

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I would have the well water tested. Before RO. As to which test, can't help you there. You could also test after the RO, but that will only show what is left in the water. What is left in the water after RO could be the problem.
 

Randy Holmes-Farley

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If the DI depletes rapidly when the TDS going to it is not that thigh, then there are very few possibilities and CO2 is certainly the most likely.

What Co2 kit and do you know it was working right?
 
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Joshbrokeit

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How quickly after they shocked(used chlorine) the well did you run the unit?

Chlorine will absolutely destroy a membrane.
Used after the chlorine smell was out of the water (3-5days). I did not test Chlorine concentration. BUT RO had Amazing performance 0-1tds. After a week it went back to the normal performance of about 9tds. So before the shock and shortly after it went back to the same performance. Membrane was replaced a few months later. Same performance from that membrane. So it may have damaged the membrane, but the only reason I brought this up is because it was odd to get such great performance. Maybe it acted like a softener of some sort??

My problem is not RO membrane damage, all three (completely separate units) had the same performance consistently.


Have you contacted support at Spectrapure?
I did. I was actually upset at the time. Because I basically got the 'that's not terrible performance' response via email. After being recommended to purchase their filters and being told they are the 'best'. I found absolutely no difference in the performance of specialize DI or RO. Just long shipping times and slightly higher pricing.

If the DI depletes rapidly when the TDS going to it is not that thigh, then there are very few possibilities and CO2 is certainly the most likely.

What Co2 kit and do you know it was working right?
Correct. I felt the same way. That's why I tested CO2. It was very low. I believe the test kit was a spectrapure brand a local reefer brought it over (not sure on if it was expired or not). It read very low. So I took measurements on Alk, PH, and Temp (using co2 calculator). I got the same results 0-1ppm. Before and after the degassing chamber and also before and after being in a storage bin. (I doubt my house CO2 is very high; normally keep my tanks between 8.1-8.3).

The only difference the degassing chamber or storage bin made was a slight drop on PPM (0-5ppm) - I'm really not sure why because from what I understand CO2 does not show up as PPM on tds meters?

Even with low CO2 I burn through resin. Which is why I am trying to figure out what I should begin testing my water for or an alternative to DI resin.



Also thank you all for responses, greatly appreciate the feedback, hopefully I can get this thing working soon.
 

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