Found out something interesting today and confused!!

reefpeeper · Mar 30, 2016

So i was making up some saltwater in a five gallon bucket today and i decided to test the tds of my ro/di water. In my storage container it measured 1ppm which i do not think is bad. Correct? I then for some reason tested the water i had put in the bucket before adding salt. It measured 17ppm!!!. Im assuming particles of whatever was left in bucket from doing water changes and things like that had affected reading. What i want to know is when i put this water into tank after mixing in salt am i really putting the 17ppm in my tank? Let me hear your thoughts.

jason2459 · Mar 30, 2016

Normally I just make sure I'm not reading 1 or more. I assume that small amount is safe.

I would safely ignore the TDS reading after putting the RODI into the bucket previously used to mix salt. At least that is my understanding of what you are doing.

After mixing salt into the RODI you're adding a very large amount of TDS.

TDS is not a measure of water quality at all. A TDS of 300 or more for some could be perfectly safe. A TDS reading of 1 could easily be deadly for others.

jason2459 · Mar 30, 2016

A good read on TDS
http://www.reefkeeping.com/issues/2004-04/rhf/feature/index.htm

reefpeeper · Mar 30, 2016

jason2459 said:
Normally I just make sure I'm not reading 1 or more. I assume that small amount is safe.

I would safely ignore the TDS reading after putting the RODI into the bucket previously used to mix salt. At least that is my understanding of what you are doing.

After mixing salt into the RODI you're adding a very large amount of TDS.

TDS is not a measure of water quality at all. A TDS of 300 or more for some could be perfectly safe. A TDS reading of 1 could easily be deadly for others.

Thanks. Thats what i thought.

Randy Holmes-Farley · Mar 31, 2016

I agree that as long as it is 1 ppm TDS or less coming out of your DI, it doesn't matter what it reads later. Tiny amounts of old salt water, salt spray dust, etc. can all boost the TDS considerably.

Hunter S Thompson · Mar 31, 2016

I'm sure your dirty bucket caused no harm. lol, 17 is not high. If your tap water came out at 17 you wouldn't even need that RO/DI unit (other than for top-off water).

AZDesertRat · Mar 31, 2016

Since saltwater is something over 32,000 TDS, 17 is literally a drop in the bucket.

ryan paggi · Mar 31, 2016

Ok maybe I'm misunderstanding this. My tds meter on my rodi reads 26 and I changed the filters 3 months ago and my storage tank water is 80. But all my tank params are perfect and I have no alge so am I missing something or is my setup bad

bobman · Mar 31, 2016

Your setup is fine most all of our storage containers will creep tds over time. From dust and all kinds of things that get dissolved in our water. All you can do is try to keep it as clean as you can.

AZDesertRat · Mar 31, 2016

What meter, is it ATC compensated and calibrated and how are you using it?
What filters did you change, what micron ranges are they, did you disinfect the system while it was down and what are all three of your TDS readings? What is your tap TDS and hardness, temperature and pressure? What is your exact measured waste ratio? How much water do you make at a time, how often and what do you store it in?
A TDS of 26 is not good.

jason2459 · Mar 31, 2016

ryan paggi said:
Ok maybe I'm misunderstanding this. My tds meter on my rodi reads 26 and I changed the filters 3 months ago and my storage tank water is 80. But all my tank params are perfect and I have no alge so am I missing something or is my setup bad

Is that 26 TDS reading coming out right after your DI stage? If so your DI is exhausted or you have channeling going on so water is bypassing the DI resin and the DI needs packed better.

AZDesertRat · Mar 31, 2016

You can't say for sure without knowing the tap and RO only TDS. It takes 3 TDS reading locations to troubleshoot a RO/DI along with all the other question I asked.

ryan paggi · Mar 31, 2016

AZDesertRat said:
What meter, is it ATC compensated and calibrated and how are you using it?
What filters did you change, what micron ranges are they, did you disinfect the system while it was down and what are all three of your TDS readings? What is your tap TDS and hardness, temperature and pressure? What is your exact measured waste ratio? How much water do you make at a time, how often and what do you store it in?
A TDS of 26 is not good.

Well I stick the tds meter in the water and read it lol I changed the membrane the carbon and 2 micron and di Cartridge filters and My tds of the tap water which is well water is 650. I didn't disinfect it while it was down I didn't even know to do that. As far as waste ratio I have no idea the waste dumps into my drain. It's set by a float in my 30gal drum and when I take water it starts filling up until it shuts it's self off. I bought the setup off amazon because I figured there all the same it would be the filters that matter and I changed them out with ones from marine depot

ryan paggi · Mar 31, 2016

I have very hard water I know that and im running it a 60psi. As far as temp goes it's just cold water. I thought it was simple just change the filters every 6 months but I'm guessing I'm way wrong. Try to bear with me guys and to help walk me thru it

jason2459 · Apr 1, 2016

AZDesertRat said:
You can't say for sure without knowing the tap and RO only TDS. It takes 3 TDS reading locations to troubleshoot a RO/DI along with all the other question I asked.

I feel confident that the TDS reading coming directly out of a DI stage that is not exhausted or channeling should be under 1ppm on a TDS meter.

jason2459 · Apr 1, 2016

ryan paggi said:
Well I stick the tds meter in the water and read it lol I changed the membrane the carbon and 2 micron and di Cartridge filters and My tds of the tap water which is well water is 650. I didn't disinfect it while it was down I didn't even know to do that. As far as waste ratio I have no idea the waste dumps into my drain. It's set by a float in my 30gal drum and when I take water it starts filling up until it shuts it's self off. I bought the setup off amazon because I figured there all the same it would be the filters that matter and I changed them out with ones from marine depot

Taking the TDS after its in a container, unless controlled, isn't reliable enough to know what the TDS is coming out of the DI stage.

Well water is often very high in CO2 which along with the high tds levels you mentioned going into the RODI filter will exhaust the DI fairly quickly.

AZDesertRat · Apr 1, 2016

To test the TDS you need to test directly from the RO membrane and DI filter.
Get yourself a clear, glass drinking water glass and wash it by hand in very hot water so it has no dishwasher soap residue or water spotting rinses.
What meter do you have and is it calibrated? Get a jug of distilled water and put some in the above glass and make sure you are at 0 or very close TDS. If need be, rinse the meter several times in distilled water to clean the probes.
Now, draw a glass of your tap water and stick the meter in the glass, let the reading stabilize, write it down and triple rinse both the meter and glass in the distilled water. Next draw a glass of water directly from the RO membrane, not from any storage vessel and again insert the meter and let it stabilize before writing the result down then triple rinsing the meter and glass in the distilled water. Finally draw a glass of RO/DI water directly from the DI, not any stored water and do it all over again. Once you have recorded the reading and triple rinsed everything in distilled water, put the meter away capped and the glass away upside down so it stays clean for next time.
What were the three TDS readings?

What are you storing your RO/DI water in? How much do you make at a time? Float valves are not really good for this since they can cause a RO to kick on and off frequently leading to TDS creep and short DI life. Try to make at least 10-15 gallons minimum and at least every 10-14 days to keep things fresh.
You need to test your waste ratio using a measuring cup and clock or watch for exactly one minute from the waste and the treated lines. Should be 4:1 waste to good.

AZDesertRat · Apr 1, 2016

Yes it could have exhausted resin but throwing resin at a bad membrane is a waste of money. You need to know the condition of the entire system, start to finish. DI is just a final polishing step, the RO does 90-98% of the work.

ryan paggi · Apr 1, 2016

Ok what kind of membrane would you suggest. Come to think of it I didn't replace that because I thought it was still good. I was thinking it was the pre filter that was the one that I needed to focus on

AZDesertRat · Apr 1, 2016

Sediment and carbon filters have very little to absolutely nothing to do with TDS. They protect the membrane from suspended particles and chlorine. TDS is in the 0.0001 micron range, sediments and carbons are hundreds to thousands of times coarser than that.
Before spending any money answer the questions I asked yesterday in post #17 so we can troubleshoot your system and where the problem lies.