Total Dissolved solids
- Thread starter h2o
- Start date
- Location
- Rockaway Park
0
- Location
- westchester
6 is not bad 0 is better i would check the filters in you ro/di maker
- Location
- Wheatley Heights, NY (long island)
the closer to zero, the better. 6 is a lot better than 43!
- Location
- Rockaway Park
change all your cartridges and di. i'm sure it'll be at zero after that, unless your meter is broken.
- Location
- Brooklyn, NY
6 is still a little too high. When my meter reads 2 I change media. My guess is that your DI canister is shot. I also agree you should calibrate your TDS meter.
Thank you all 4 the advice. the TDS meter is brand new got it at MACNA and the lady at the RODI stand calibrated it 4 me I also got all new cartridges so im going to change them and see what reading i get after that .
- Location
- Ossining, NY
I would also check a few other things - TDS before DI resin (called an RO bypass) and if you can on the output of the carbon block (little more complicated) this will tell you what you have after the RO filter and what you have before the RO filter and after the prefilter and carbon block. All good points of measurement.
It would also help to know a little more about your setup - what kind, how many stages, what type of cartidges you may be using, thier ages, colors etc.
Hope that helps,
House
It would also help to know a little more about your setup - what kind, how many stages, what type of cartidges you may be using, thier ages, colors etc.
Hope that helps,
House
The RODI i have is Pure-Flo 2 by Coralife 50gal per day 4 catridges go in it. The old membrane was by GE infrastructure TMF-50 i replaced it with a Filmtec membrane,the other ones had no names on them i changed them 1st sediment filter 1micron,2nd no name, 3rd nuclear grade di resin. then i tested again , 1 tap water 043 then after 2nd filter comes out 010 and after the last one 000 
- Location
- Ossining, NY
- Location
- Forest Hills
after 1st pass (RO) the tds should be depended on what the membrane rejection rate is. i.e. if 98%(average) then 2 ppm. the other filters should reduce it to 0 ppm.
find out what your mrr is. this is also how you can tell if your membrane needs to be replace.
i will give +/- 1ppm for margin of error on the tds meter.
find out what your mrr is. this is also how you can tell if your membrane needs to be replace.
i will give +/- 1ppm for margin of error on the tds meter.
Last edited:
Buckeye Field Supply
Sponsor
- Location
- On the Internet
A good rule of thumb is to replace your sediment filter and carbon block after six months. A more precise way to maximize the useable life of these two filters is to use a pressure gauge to identify when pressure reaching the membrane starts to decline. This is your indication one or both of the filters is beginning to clog.
Also be cognizant of the chlorine capacity of the carbon block. The Matrikx+1 (“Chlorine Guzzler”) for example will remove 99% of chlorine from 20,000 gallons of tap water presented at 1 gpm. Original equipment suppliers commonly provide carbon cartridges rated at 2,000 to 6,000 gallons.
Regarding your RO membrane and DI resin, use your TDS meter to measure, record, and track the TDS (expressed in parts per million) in three places:
1. Tap water
2. After the RO but before the DI
3. After the DI.
The TDS in your tap water will likely range from about 50 ppm to upwards of 1000 parts per million (ppm). Common readings are 100 to 400 ppm. So for sake of discussion, let's say your tap water reads 400 ppm. That means that for every million parts of water, you have 400 parts of dissolved solids. How do we go about getting that TDS reading down to somewhere near zero?
If you do some experimenting with your TDS meter, you'll note that your sediment filter and carbon block filter (collectively called “prefilters”) do very little to remove dissolved solids. So with your tap water at 400 ppm, you can measure the water at the “in” port on your RO housing and you'll see it is still approximately 400 ppm.
The RO membrane is really the workhorse of the system. It removes most of the TDS, some membranes to a greater extent than others. For instance, 100 gpd Filmtec membranes have a rejection rate of 90% (i.e., they reject 90% of the dissolved solids in feed water). So the purified water coming from your 100 gpd membrane would be about 40 ppm (a 90% reduction). Filmtec 75 gpd (and below) membranes produce less purified water (aka “permeate”), but have a higher rejection rate (96 to 98%). The life span of a RO membrane is dependant upon how much water you run through it, and how dirty the water is. Membranes can function well for a year, two years, or more. To test the membrane, measure the total dissolved solids (TDS) in the water coming in to the membrane, and in the purified water (permeate) produced by the membrane. Compare that to the membrane’s advertised rejection rate, and to the same reading you recorded when the membrane was new. Membranes also commonly produce less water as their function declines.
After the RO membrane, water will flow to your DI housing. DI resin in good condition will reduce the 40 ppm water down to 0 or 1 ppm. When the DI output starts creeping up from 0 or 1 ppm to 3 ppm, 5 ppm, and higher, you know that your resin needs to be replaced. Sometimes people complain that their DI resin didn't last very long. Often the culprit is a malfunctioning RO membrane sending the DI resin “dirty” water. This will exhaust the resin quicker than would otherwise have been the case. Sometimes the problem is poor quality resin – remember that all resins are not created equal!
Russ @ BFS
Also be cognizant of the chlorine capacity of the carbon block. The Matrikx+1 (“Chlorine Guzzler”) for example will remove 99% of chlorine from 20,000 gallons of tap water presented at 1 gpm. Original equipment suppliers commonly provide carbon cartridges rated at 2,000 to 6,000 gallons.
Regarding your RO membrane and DI resin, use your TDS meter to measure, record, and track the TDS (expressed in parts per million) in three places:
1. Tap water
2. After the RO but before the DI
3. After the DI.
The TDS in your tap water will likely range from about 50 ppm to upwards of 1000 parts per million (ppm). Common readings are 100 to 400 ppm. So for sake of discussion, let's say your tap water reads 400 ppm. That means that for every million parts of water, you have 400 parts of dissolved solids. How do we go about getting that TDS reading down to somewhere near zero?
If you do some experimenting with your TDS meter, you'll note that your sediment filter and carbon block filter (collectively called “prefilters”) do very little to remove dissolved solids. So with your tap water at 400 ppm, you can measure the water at the “in” port on your RO housing and you'll see it is still approximately 400 ppm.
The RO membrane is really the workhorse of the system. It removes most of the TDS, some membranes to a greater extent than others. For instance, 100 gpd Filmtec membranes have a rejection rate of 90% (i.e., they reject 90% of the dissolved solids in feed water). So the purified water coming from your 100 gpd membrane would be about 40 ppm (a 90% reduction). Filmtec 75 gpd (and below) membranes produce less purified water (aka “permeate”), but have a higher rejection rate (96 to 98%). The life span of a RO membrane is dependant upon how much water you run through it, and how dirty the water is. Membranes can function well for a year, two years, or more. To test the membrane, measure the total dissolved solids (TDS) in the water coming in to the membrane, and in the purified water (permeate) produced by the membrane. Compare that to the membrane’s advertised rejection rate, and to the same reading you recorded when the membrane was new. Membranes also commonly produce less water as their function declines.
After the RO membrane, water will flow to your DI housing. DI resin in good condition will reduce the 40 ppm water down to 0 or 1 ppm. When the DI output starts creeping up from 0 or 1 ppm to 3 ppm, 5 ppm, and higher, you know that your resin needs to be replaced. Sometimes people complain that their DI resin didn't last very long. Often the culprit is a malfunctioning RO membrane sending the DI resin “dirty” water. This will exhaust the resin quicker than would otherwise have been the case. Sometimes the problem is poor quality resin – remember that all resins are not created equal!
Russ @ BFS
Buckeye Field Supply
Sponsor
- Location
- On the Internet
remember that your prefilters (the filters before the membrane) don't remove tds. TDS is removed primarily by the RO membrane, and the remaining little bit is removed by the DI resin.
A reading of 6 tells me your DI resin is exhausted.
Russ
A reading of 6 tells me your DI resin is exhausted.
Russ
- Location
- Staten Island
In Staten Island my tds is 29 before unit and 0 after I change my prefilter every 300 gallons or when it looks like the chocolate swirl, changing the carbon block every other prefilter change.. Sometimes I let it go to all chocolate..
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