RODI Question
- Thread starter hbtl_ofndr
- Start date
it all depends on how much water you make and how often you make it...i change my filters every 3 to 4 months...cause i make 35 to 40 gallons every other week and sometimes even more cause i hook people up with ro/di water or salt mix it for them since there is no more local stores around here in corona besides in riverside...
It really depends how much water I am making. if I make a ton of water then I go through resin and membrane a lot quicker. Also my tds going into the unit varies during the year. Sometimes its 350 tds and other times its 475.
Best thing is to always moniter the tds at three location.
1-Going into the unit
2-right out of the membrane
3-after the di
57 tds out does not tell you if the membrane is bad or just exhausted di.
Best thing is to always moniter the tds at three location.
1-Going into the unit
2-right out of the membrane
3-after the di
57 tds out does not tell you if the membrane is bad or just exhausted di.
I don't feel I go through that much water. Between WC and ATO maybe 120G a month.
Ordered all new prefilters (sediment, GAC, and carbon block) as well as color changing resin. I can't imagine the RO membrane or inline carbon being bad after 3 months.
So which is more important - measuring the in water or the water coming out of the RO membrane? Currently my meter is hooked up to raw in, and after resin out.
Maybe I'm dumb and have something hooked up wrong??
Ordered all new prefilters (sediment, GAC, and carbon block) as well as color changing resin. I can't imagine the RO membrane or inline carbon being bad after 3 months.
So which is more important - measuring the in water or the water coming out of the RO membrane? Currently my meter is hooked up to raw in, and after resin out.
Maybe I'm dumb and have something hooked up wrong??
I don't feel I go through that much water. Between WC and ATO maybe 120G a month.
Ordered all new prefilters (sediment, GAC, and carbon block) as well as color changing resin. I can't imagine the RO membrane or inline carbon being bad after 3 months.
So which is more important - measuring the in water or the water coming out of the RO membrane? Currently my meter is hooked up to raw in, and after resin out.
Maybe I'm dumb and have something hooked up wrong??
Ordered all new prefilters (sediment, GAC, and carbon block) as well as color changing resin. I can't imagine the RO membrane or inline carbon being bad after 3 months.
So which is more important - measuring the in water or the water coming out of the RO membrane? Currently my meter is hooked up to raw in, and after resin out.
Maybe I'm dumb and have something hooked up wrong??
Measuring after the membrane and before the Di is important as it will let you know if your membrane is going bad. lets say you have a membrane with a 95% rejection rate. If your TDS going into the unit is 100 then coming out of the membrane it SHOULD be 5 right? But if the water coming out is 30 then it is going bad and that will exhaust your resin much quicker. So checking there lets you know the status of your membrane. The DI resin is meant to just polish the last bit of remaining tds. Sometimes you only need to replace the resin and not the membrane.
Personally I dont think you need to stress until the tds creeps above 8 ppm.
- Joined
- Nov 2, 2009
- Messages
- 1,210
- Likes
- 81
- Points
- 48
From my understanding, your prefilters, the ones you ordered, will do next to nothing in reducing your TDS levels.. they are there mainly to protect your RO membrane. If your TDS is 57, you have bigger issues than your prefilters. Even if you have a crappy 90% rejection rate and A TDS of 500 coming in.. you'd be at 50 TDS pre-di. 75gpd filmtec membranes typically have a 98% rejection rate, not worse than 96%. Perhaps your membrane isn't fully seated, or your membrane container is cracked..
To answer your question.. I have psi gauges before the sediment filter and after, and when there is a significant psi loss, then I change the sediment filter. As for carbon, I have chlorine test kits and check the water post carbon regularly.. changing them regularly is a waste of money IMO unless there is a reason they need to be changed. I typically make 400-500 gallons per month and find the filters last longer than you'd expect..
To answer your question.. I have psi gauges before the sediment filter and after, and when there is a significant psi loss, then I change the sediment filter. As for carbon, I have chlorine test kits and check the water post carbon regularly.. changing them regularly is a waste of money IMO unless there is a reason they need to be changed. I typically make 400-500 gallons per month and find the filters last longer than you'd expect..
When I first setup my ro/di I was getting 11 tds before my di chamber and 24 tds AFTER my di chamber. After some research I found out that my di resin wasnt properly packed. I purchased a new di resin, packed it really tight and BOOM! 0 tds! I would test the tds going into the unit, and then again before it goes into the di resin, and ofcourse after the di.
If you are not testing Tds in and Tds out of membrane then you may not be solving the problem. If your membrane is shot and you only change out the resin then your DI is doing the job of the membrane and will be quickly depleted. You need to see what the Tds out of the membrane is. You can just remove the resin, run it for a few minutes and then see what the Tds is out of the unit
I'll move the IN on the TDS meter between the membrane and DI stage later today once I can get a coupler. Right now I'm totally confused:
Changed my DI resin and TDS dropped to 4ppm. prefilters came in yesterday so I changed sediment, GAC and carbon block. After replacing and running about 15G through the system my TDS went up to 17ppm.
Changed my DI resin and TDS dropped to 4ppm. prefilters came in yesterday so I changed sediment, GAC and carbon block. After replacing and running about 15G through the system my TDS went up to 17ppm.
I think you need to run it more than 15 gal before you get an accurate reading. I have one of those 5 stage brs unit too and its been 3 months and my tds reading just went from 0 to 2 in the last week. I used about 40-50 gals a week. I believe the resin needs to be changed every 3-6 months depending on use but the carbon stuff maybe once a year.
A good rule of thumb is to replace your sediment filter and carbon block after six months. A more precise way to maximize the usable 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. A good 0.5 micron carbon block for example will remove 99% of the chlorine from 20,000 gallons of tap water presented at 1 gpm. Some original equipment suppliers commonly provide carbon cartridges rated at 2,000 to 6,000 gallons. Remember that all the water you process, both waste water and purified water, go through the carbon block.
Regarding your RO membrane and DI resin, use your total dissolved solids (TDS) meter to measure, record, and track the TDS (expressed in parts per million [ppm]) in three places: 1) tap water, 2) after the RO but before the DI, and 3) after the DI.
The TDS in your tap water will likely range from about 50 ppm to upwards of 1000 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 (collectively called prefilters because the treat the water before it reaches the membrane) 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 the 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 purified water (a.k.a. permeate) more slowly, but have a higher rejection rate (96 to 98%). The lifespan of a RO membrane is dependent 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 TDS in the water coming in to the membrane, and in the purified water (permeate) produced by the membrane. Compare that to the membranes advertised rejection rate, and to the same reading you recorded when the membrane was new. Membranes also commonly produce purified water more slowly as their function declines.
After the RO membrane, water will flow to your DI housing. DI resin in good condition will reduce the TDS in the RO water down to 0 or 1 ppm. When the DI output starts creeping up from 0 or 1 ppm, 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.
Additionally, dont forget to sanitize the entire system at least once per year, and wash and lube your housing o-rings with food-grade silicone grease every filter change.
Russ
Also be cognizant of the chlorine capacity of the carbon block. A good 0.5 micron carbon block for example will remove 99% of the chlorine from 20,000 gallons of tap water presented at 1 gpm. Some original equipment suppliers commonly provide carbon cartridges rated at 2,000 to 6,000 gallons. Remember that all the water you process, both waste water and purified water, go through the carbon block.
Regarding your RO membrane and DI resin, use your total dissolved solids (TDS) meter to measure, record, and track the TDS (expressed in parts per million [ppm]) in three places: 1) tap water, 2) after the RO but before the DI, and 3) after the DI.
The TDS in your tap water will likely range from about 50 ppm to upwards of 1000 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 (collectively called prefilters because the treat the water before it reaches the membrane) 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 the 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 purified water (a.k.a. permeate) more slowly, but have a higher rejection rate (96 to 98%). The lifespan of a RO membrane is dependent 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 TDS in the water coming in to the membrane, and in the purified water (permeate) produced by the membrane. Compare that to the membranes advertised rejection rate, and to the same reading you recorded when the membrane was new. Membranes also commonly produce purified water more slowly as their function declines.
After the RO membrane, water will flow to your DI housing. DI resin in good condition will reduce the TDS in the RO water down to 0 or 1 ppm. When the DI output starts creeping up from 0 or 1 ppm, 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.
Additionally, dont forget to sanitize the entire system at least once per year, and wash and lube your housing o-rings with food-grade silicone grease every filter change.
Russ
When did you get all smarty pants and not share with us????? Okay for starters you have the last pressure gauge on the last DI or what canister exactly? What rodi unit are you using?
What do you use to test For Chlorine and you test it at the last exit?
You have me thinking here.
I change my filters out around every 4-6 months. Pre filters in our city have to be changed before the others cause they get super filthy!
My buddy goes through 100 gallons a day and changes his pre filters every month. I guess the golden state water company really has disgusting well water.
Also wanted to add that the Tds meters in our online are pretty crappy and not very accurate. I'd like to learn more about when you should change filters. I would change em when my exit Tds on my Hanna is above 7, which is 0 on the inline.
What do you use to test For Chlorine and you test it at the last exit?
You have me thinking here.
I change my filters out around every 4-6 months. Pre filters in our city have to be changed before the others cause they get super filthy!
My buddy goes through 100 gallons a day and changes his pre filters every month. I guess the golden state water company really has disgusting well water.
Also wanted to add that the Tds meters in our online are pretty crappy and not very accurate. I'd like to learn more about when you should change filters. I would change em when my exit Tds on my Hanna is above 7, which is 0 on the inline.
I mix 50g of RODI every month along with the daily drinking supply. I have a dual TDS meter that measures the water before the DI stand and after the DI stage. Drinking water reading is between 10-20. The after DI stage should always be 0. I've had to change the resin about once every 9 months. It all depends on your usage.
