How to deal with high TDS reading/

[Boxster]

I installed my RO/DI system over the weekend. It is from filterdirect from ebay.
On Saturday, I check my TDS reading on the RO water and is reading about 11ppm. Knowing my tap water used to be 230ppm, I am pretty happy.
On Sunday morning, I dispense some RO/DI water and lo and behold I tested to be 19ppm??? Knowing that my RO/DI TDS should never be higher than my RO water, i retested my RO water and it turn out to be 20ppm? I retest my tap water and now it reads 350ppm!! I know my TDS is good and calibrated because I have a RO/UV water that I know is about 3ppm. I use my TDS meter to test that RO/UV and it is consistently reads 3ppm no matter how many time I test it.

Now, my question. Does the city water quality flunctuate all the time??? Does my DI resin need some time to kick in so that it is actually doing something? Even so, 20ppm at the RO is still high for my DI to get to 0ppm? So any solution. Add another RO/DI in series??

 

[reefrunner69]

Now, my question. Does the city water quality flunctuate all the time???

I honestly don't know, you would need to ask your water company. Are you sure your not on a well? That TDS seems high for treated water.

Did you let the RO run for a couple of hours prior to using the water? There are preservatives in the RO membrane as well as the DI (I suspect) that need to be flushed prior to using the water.

Not trying to talk down to you, but on my first RO unit I did this, are you sure them membrane is in there? I left mine out once and was stunned at how fast that sucker could make water, LOL. Also make sure the membrane is seated correctly.

 

[reefrunner69]

Oh yeah, at an RO dishcarge of 20ppm your DI should reduce the TDS to 1 or 0 after that.

Your getting a 94% rejection rate on your RO but only gettin 5% rejection rate on your DI.

 

[cmor1701d]

My city supplied water ranges from aprox 180 to over 230 tds. Depends on the day and time of day. My RO/DI is always 0 - 1. Anything higher turns out to be a dirty container

 

[Boxster]

I don't understand. If I am getting 20ppm on the RO, and wants the RO/DI to let says 1, then the DI rejection should be 95% right? (20-1)/20.

What is normally the rejection for DI Resin?

Also, talked to FilterDirect on this. He was saying that if you have a storage tank on the RO side, you need to limit your ball valve at the output of the DI so that the water flow from the storage tank being pressurize will not flow too quickly through the DI resin and limit its effectiveness.

I tried this by turning by ball valve at the output of the DI to nearly close to Off position such that water is trickling out very slowly. However, I got 12 at the TDS reading. So the rejection is only (20-12)/20 = 40%.

I re-test my tap water. It is still 350ppm???? I called the city water and they said that they don't have a requirement to test TDS. The last time they tested is in 1997, and it reads 500-550ppm!!!.

 

[reefrunner69]

What is normally the rejection for DI Resin?

Ususally it should be between 95-99%

Also, talked to FilterDirect on this. He was saying that if you have a storage tank on the RO side, you need to limit your ball valve at the output of the DI so that the water flow from the storage tank being pressurize will not flow too quickly through the DI resin and limit its effectiveness.

This would make sense to me, slower flow through the DI would allow it to remove more TDS

I tried this by turning by ball valve at the output of the DI to nearly close to Off position such that water is trickling out very slowly. However, I got 12 at the TDS reading. So the rejection is only (20-12)/20 = 40%.

Use a known measure of water and time it, make sure it is not producing more than it is rated for.

I receive my RO/DI from them today and will be installing it this afternoon, so I am very interested in this thread, please keep it updated, once I start producing some water, I will post my results as well.

 

[reefrunner69]

I thought something didn't make sense I just got my RO/DI w/booster pump assembly (anyone wanna come hook this sucker up for me?) and in the installation kit is two ball valves, one for the tank and one for the DI. Turn the ball valve off to the tank so it cannot push any water out while your making DI water, then you can run the ball valve on the DI wide open.

 

[loganj]

There should be a check valve on the pressure tank to prevent water from back flowing through the DI chamber. There should be a float valve connected on the storage container that will signal a shut off solenoid. The shut off solenoid will kill the water on the supply side until there is a pressure drop either from the float valve or the pressure tank. If you are getting 12-15 TDS out of the RO, it should be 0-1 out of the DI. Water that has been sitting in the unit for a while will read higher. Let it run for about 5 minutes and then check it...that's the only way you'll get an accurate reading. If your RO membrane is putting out water at a higher TDS than 15 or so, you might want to add a second DI chamber to the unit to polish the water down to 0 TDS.

 

[reefrunner69]

There is no float valve in the tank, there is an auto shut off in the unit that should shut off the water when it reaches a certain pressure. I'm running a booster pump with mine, so I had to remove the auto shut off valve and hook the solenoid and the pressure switch in it's place. The way the unit is designed, I don't see how you could put a check valve into the DI to keep water in the tank from going through the DI. Only one line goes to the tank, it serves both in and out. In order to put a check valve on it....you would not get DI water at all or you wouldn't get tank water, one or the other. There is a ball valve attatched to the top of the tank, whhen you want to make DI water for the fish, simply turn the ball valve off and all you will get is fresh made RO/DI water. There is a check valve that prevents the DI water from back flowing into the RO.

 

[loganj]

OK, I think I see what you're talking about. The way I would set that up is to have the line for the pressure tank tee off between the RO and the DI. That way, you have RO water going into the drinking water tank. There would be an inline check valve or a check valve at the pressure tank inlet so that RO water could only travel in. If there is only one line going into the pressure tank and it's serving as an in/out line, the check valve would need to be between the RO and the tee up to the faucet. The line coming out of the DI would go to the float valve in the DI water storage container. If this is open and the pressure tank is full, water would automatically flow through the DI into the storage container. The pressure switch for the booster pump should be set just below the cut off pressure for the shut off solenoid...that way, it kicks out just before the the solenoid shuts down the water supply. At least, that's how I'd set it up. 8O

 

[reefrunner69]

Well got it up and running.....

Water going into RO 220 TDS, water coming out...15, I expect 0 or 1 out of the DI. Just a FYI, the water out of the DI read 50 when I first tested, I was really disappointed, then I thought, "Hey stupid, rinse the glass out with the RO water, did it three consecutive times and it comes out 15, so make sure you rinse your glass in the water your testing before you test!!

I am hoping the TDS will go down as the tank flushes more. For how the solenoid and pressure switch are set up...look at my booster pump thread, just updated it. The diagram I have shows a check valve at the RO discharge, doesn't specify anywhere else, but the diagram that shows the check valve is for a straight RO system not an RO DI. I know when I make RO/DI water...I plan to turn the ball valve off on the pressure tank and turn it back on when I'm done

 

[Aztlan]

When I got my RO/DI unit I had to run 12 gallons threw it, with out the DI Resin. So it would not be contaminated by the junk on the new membrane. After the membrane was flushed, I put the DI Resin in and I always get a TDS reading of 0.

 

[reefrunner69]

100 gallons threw it,

Everything I've ever read has said a few gallons is all that's needed to flush the presevatives. I filled my pressure tank twice and discharged it, about 6-8 gallons, now it's time to make some DI water

 

[reefrunner69]

Hmmm, I just started making DI water, turned the valve off at the tank and running through the sediment filters and then the RO then the DI, my initial DI water was 50ppm 8O after running it for a few minutes it dropped to 20, but the water in the tank is still 15. This really makes no sense, I suppose the DI had to be filled with the water with the preservatives for the membrane, but how long should it take to flush? I'm gonna let it run down the drain and periodically test it see what I get. if it is not giving good results after a few hours of flushing I'll be on the phone to filterdirect. It has to be a flushing issue though, there is no reason for the DI water to be higher than the straight RO, you can't make me believe the post RO carbon filter removes more TDS than the DI.

 

[loganj]

Let it run a while. I think you'll see the levels drop. New DI cart and all. Mine did something like that at first. I don't think I flushed it long enough as I went through the first DI cart in just a few weeks. Since I changed it, this one seems like it's going to last a lot longer. TDS is a little high when I first start the unit, but it rapidly drops to 0.

 

[Boxster]

Reefrunner, what is your results. I talked to the FilterDirect guy again and he mentioned that some DI resin that they shipped with is not good. That is why I am getting like 40% rejection. He is sending me a better one next week. Just like to compare as well, what is the manufacturer or part number of your DI resin. If mine is the same DI, and you are getting good rejection, then something is wrong with my setup.

But thanks for the idea. I will try to shutoff the ball valve at the tank and then turn my DI ball valve open. What is your flow rate through the DI when you shutoff the ball valve at your tank. Mine is a slow stream of water.

When I did the experiment in my previous post getting the 12ppm out of DI, I actually empty the tank my turning my Ro faucet full on until the water stop flowing. Then I turn off my RO faucet and turn on the DI ball valve. However, I never close the Tank ball vlave though. But this should be the same as the water will then flow from the tap through RO/DI right? I still got 12ppm!!!

Is 12ppm ok for my fish tank???/

 

[Boxster]

Sorry for the repeated post, seems like the website is repeating my previous post at differemt time. Weird.

Ok, Reefrunner, that is what I experience when I started this thread. The DI someitmes read higher than the RO ppm. It make no sense to me as well. I flush out about 15 gallons already, still read 12ppm at my RO/DI, and 20ppm at RO. I washed my glass with RO/UV water that reads 3ppm. but results the same- 12ppm at RO/DI.

FilterDirect said that the DI resin comes with recent unit is not good. Rejection is bad. They are sending me new onw next week. But let get the serial number and the model for your DI and let compare. I suspect is the same DI since we got our unit about the same time.

 

[reefrunner69]

Is 12ppm ok for my fish tank???/

Yes, you might experience a tad more algae than if the DI was filtering correctly, but to be honest, if your concerned use the water that measures 3ppm

I looked and did not see a part number or serial number on my DI cart. Where on the label is it located, if I can get to it without tearing it apart, I'll get it and post it here.

 

[reefrunner69]

Reefrunner, what is your results. I talked to the FilterDirect guy again and he mentioned that some DI resin that they shipped with is not good. That is why I am getting like 40% rejection. He is sending me a better one next week. Just like to compare as well, what is the manufacturer or part number of your DI resin. If mine is the same DI, and you are getting good rejection, then something is wrong with my setup.

I'm certain it is the DI, I folloowed the instalation instructions to a tee and went over them again and again to make sure it was flowing the way it should. FWIW, I get 15 ppm out of the RO and I get 16 out of the DI. The accuracy of my handheld unit is ±1, so basically it is the same reading. I get 0% rejection from my DI. I spoke with Oscar at filterdirect this afternoon and he said I should be getting 0-5 after the DI, he is sending me a new one as well. FWIW, the service from this company has been outstanding, they have answered every email and want to get my filter right.

 

[Boxster]

This is the picture of my DI resin