ChrisB
Guest
I just got my RODI unit running full time and so far the TDS reading from my tap is 203 and after the DI filter it is reading 13-15. Is this acceptable to use in my tank?
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TDS readings (1 Viewer)
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G
Guest
You should be closer to a 0 reading coming out of your DI. What is the TDS reading out of the RO? What gpd membrane is it?
Are you using a clean container to run your permeate water in to test TDS?
Are you using a clean container to run your permeate water in to test TDS?
ChrisB
Guest
Its a 100gpd that came with the unit and I am using a clean glass to test the parameters. I am going to run it for a few hours and test again. I just checked the readings before and after the Di unit and came up with 10 now.
AggieBrandon
Guest
you should let the first gallon or so of permeate water go down the drain and then test the water.
BNH
BNH
G
Guest
100 gal from who? If it lets 10% through it will use your DI resin up faster. We had to swap our membrane out for a lower rate so it would not let to much junk past to save our DI resin.
yellowbelley
Guest
sorry to highjack
but is DI resin needed for a reeftank?
can i only use a RO filter?
but is DI resin needed for a reeftank?
can i only use a RO filter?
fishcraze
Lifetime Member
may not be the case, but just my experience.. when testing DI water to that low ppm, I'd use a clean/ new cup and flush it w/ DI water first to make sure no dirty stuffs in the cup that can mesh up your test.. since you are talking about a very low ppm mearsurement. little impurities can affect your results big time 
BTW, my DI water is ~ 0 - 2ppm when the DI filter is still good, and I replaced mine when the ppm came up to ~20ppm.
BTW, my DI water is ~ 0 - 2ppm when the DI filter is still good, and I replaced mine when the ppm came up to ~20ppm.ChrisB
Guest
Narkon said:
I ordered the 6 stage RO+DI Maximux unit from Aqua-Safe. I'll probably go down to a 50gpd after once this membrane needs replacing, I just don't have a need for that volume of water. Guess I could let me kids set up a RODI water stand instead of a lemonade stand.
G
Guest
Something else I learned about my RO/DI system - if you have the one with the storage tank for drinking water, close the valve to the storage tank and drain the lines for a minute before taking your sample to test. The storage tank contributes to what the manufacturer called "TDS creep", which is a nice way of saying that crud accumulates in the storage tank and over time will throw off your TDS reading.
fishcraze
Lifetime Member
You may need to think twice about that if you EVER EVER upgrade your tank to a bigger size- and most reefers end up that way
I used to have the 50gpd and it made me feel like it took forever to fill up a 180gal tank! Love the 100gpd unit now.. only take a few hours to fill up my salt resoivor for water changes.. The DI resin on my 100gpd last ~15 months- which is not too bad to me.Wildfire
Guest
FWIW:
I've got 0287 In, 0003 Out
Of my 6 stage RO/DI (assuming my TDS is right)
I've got 0287 In, 0003 Out
Of my 6 stage RO/DI (assuming my TDS is right)
RobertR
Guest
Hi, I just wanted to add my two cents. I recently had problems with my 5 stage R/O filter I purchased off Ebay. My tap water was a little over 300 TDS and I could never get a TDS reading lower than 018 out of my new R/O filter? I even went to Home depot and bought new filters only to get a TDS reading of 015 after running about 20 gallons through my system?
I than decided to called Russ over at BuckeyeFieldsupply for help. Russ determined that the R/O membrane was not the right kind and that I needed a new sediment filter etc. I ordered new filters Charcoal, Sediment, and D/I and now I'm getting 000 TDS. WOW!
I should have gone to Russ in the first place, it would have saved me time and money. He explained what the problem was and walked me through getting the problem resolved. Super job!
I than decided to called Russ over at BuckeyeFieldsupply for help. Russ determined that the R/O membrane was not the right kind and that I needed a new sediment filter etc. I ordered new filters Charcoal, Sediment, and D/I and now I'm getting 000 TDS. WOW!
I should have gone to Russ in the first place, it would have saved me time and money. He explained what the problem was and walked me through getting the problem resolved. Super job!
ChrisB
Guest
fishcraze said:
You may need to think twice about that if you EVER EVER upgrade your tank to a bigger size- and most reefers end up that way
If I ever upgrade? I was ready for a bigger tank a month after this one was finished.
Good advice though I 'll hang onto this one until it needs replacing which I am sure will be after I get a larger tank. BTW readings are now down to 5ppm, which is just as good if not better than the H2O I have been buying. Mikester - followed your advice and the readings dropped in half after turning off the storage tank. I'll leave that for filling up water jugs for the fridge.
K
Kabuto
Kinda newbie question. Why get down to 0 tds. I had water from Home Depot measure 2ppm on the TDS but have phosphates. My old RO was around 29ppm and did better (new filter and membrane now get 5ppm). I know RO gets rid of a lot of stuff but is there a line at which ppm doesn't matter. Basically I guess I am trying to say how would a DI getting me down to 0 ppm improve my tank.
My RO tank raises my TDS reading from 5ppm to 25ppm. I usually run my tank water to a fill-up jug for top off and do water changes straight from new RO water that gets me the 5 ppm.
My RO tank raises my TDS reading from 5ppm to 25ppm. I usually run my tank water to a fill-up jug for top off and do water changes straight from new RO water that gets me the 5 ppm.
Buckeye Hydro
Guest
I read through all the posts above - I wasn't going to post a reply but it looks like the following might help folks.
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.
With those three reading, and especially if you take the readings periodically and write them down, you can go a long way towards troubleshooting your system.
If anyone's interested in further discussion on how to interpret the three numbers, let me know here and I'll be happy to post more info - don't want to post a bunch of discussion everyone is already up to speed on.
Russ
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.
With those three reading, and especially if you take the readings periodically and write them down, you can go a long way towards troubleshooting your system.
If anyone's interested in further discussion on how to interpret the three numbers, let me know here and I'll be happy to post more info - don't want to post a bunch of discussion everyone is already up to speed on.
Russ
DonnieKim
Guest
I'm soon to purchase a ro/di unit and would be interested in more education on the subject!
Thanks Russ!
Donnie
Thanks Russ!
Donnie
Buckeye Hydro
Guest
Not a problem.
Let's start with the points in my last post:
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 ppm. Common readings are 100 to 400. So for sake of discussion, let's say your tap water reads 400. That means that for every million parts of water, you have 400 parts of dissolved solids.
How do we go about getting that 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 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 its 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 ratio 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 permeate, but have a higher rejection ratio (98%).
If you measure the TDS in your system after the RO membrane, and before the DI housing, you'll be able to measure the rejection rate of your membrane. A declining rejection rate is a good way to tell when your membrane needs to be replaced.
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. Usually 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.
Russ
Let's start with the points in my last post:
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 ppm. Common readings are 100 to 400. So for sake of discussion, let's say your tap water reads 400. That means that for every million parts of water, you have 400 parts of dissolved solids.
How do we go about getting that 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 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 its 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 ratio 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 permeate, but have a higher rejection ratio (98%).
If you measure the TDS in your system after the RO membrane, and before the DI housing, you'll be able to measure the rejection rate of your membrane. A declining rejection rate is a good way to tell when your membrane needs to be replaced.
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. Usually 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.
Russ
DonnieKim
Guest
Very easy to understand Russ!
I have been using water from Kroger's machine for my tanks. I need to get a TDS meter so as to find my ppm from this water source. I know sometimes it's good and sometime's it's not, I can tell from the way my tank reacts when I do water changes. I am eventually going to buy a ro/di unit and make up my own water. I appreciate the time you took to educate me/us on this subject.
I have been using water from Kroger's machine for my tanks. I need to get a TDS meter so as to find my ppm from this water source. I know sometimes it's good and sometime's it's not, I can tell from the way my tank reacts when I do water changes. I am eventually going to buy a ro/di unit and make up my own water. I appreciate the time you took to educate me/us on this subject.
lesd
Supporting Member
FWIW, the membrane I'm using now is a 60GPD one from spectrapure and it has a great rejection ratio. 520 PPM in, 2 PPM out.
Be aware that the output of the RO membrane has more TDS right after you turn it on. Mine usually spikes up somewhere between 10-20PPM and comes down over the first 15 minutes or so of use.
Be aware that the output of the RO membrane has more TDS right after you turn it on. Mine usually spikes up somewhere between 10-20PPM and comes down over the first 15 minutes or so of use.
G
Guest
lesd said:
You should be flushing a new membrane for about 40 minutes prior to using the permeate. Also you should not run the permeate through your DI until after flushing the membrane.
