TDS range

[mling]

I have had basic a air water & Ice RO/DI unit, with no TDS, for about 5 year before I decided to upgrade to a Typhoon III Extreme. For the last 5 years, I would only change my filters as recommended, yearly or 3 years for the membrane and all was well. I did not even know what TDS was; sometimes, no information is better .

I hooked up my TyphoonIII on May 2nd. The TDS “after” was 0, the “before” was in the hundreds. I was not even sure if the TDS alarm was working since neither the green or red LED turned on. Good news is that I now know the TDS alarm works; as of a few days ago. Bad news is that my TDS is now all over the place, currently it is 75ppm. I got is back under 10ppm after flushing both the unit i.e. open the membrane and DI bypass valve. After a day, the alarm when off again and TDS is back to over 50ppm. Flush for about 30 mins and it is under 10ppm again, but now after just a few hours it is back to over 50ppm.

What range do most of you find acceptable for TDS ?

Since my unit is less than a month old, I find it hard to believe that I need to change filters.

Would any of these have to do with spring time flushing of our county water supply ? I know I did get the yearly message with our water bill to expect possible cloudiness in our drinking water

 

[Ben1]

When I see my TDS go from 0 to 1 I change my DI filter and when I can see the floss filter is pretty dark it gets changed. I do the carbon block every two floss filter changes. Do you know before and after membrane tds numbers?

 

[Anonymous]

When I see my TDS go from 0 to 1 I change my DI filter and when I can see the floss filter is pretty dark it gets changed. I do the carbon block every two floss filter changes. Do you know before and after membrane tds numbers?

Sounds about right. I usually check the RO membrane if the output is 20.0 ppm or more. The tap water is about 400 ppm, and after it goes thru the RO and DI, it is around 0.125ppm or lower, but I usually let it slide up to 1.5 until I dump the resin in the bucket.

 

[mling]

Is it possible that I got a bad membrance since this is a new unit ?

 

[Ben1]

Maybe but it also might not be seated properly in the housing. No way of knowing if its the membrane with out knowing the before membrane TDS and after membrane TDS, with these numbers you can figure out the rejection rate and use this to determine if it is a membrane issue or something else. Does your unit have a pressure gauge?

 

[mling]

Yes I have a pressure gauge that is working fine. The "before" is 100 to 200ppm, today the "after" is in the 70's. The thing that confuses me is the it was working great for at least the first 2 to 3 weeks, don't even know what the "before" is since the "after" was always 0.

 

[Anonymous]

Yes I have a pressure gauge that is working fine. The "before" is 100 to 200ppm, today the "after" is in the 70's. The thing that confuses me is the it was working great for at least the first 2 to 3 weeks, don't even know what the "before" is since the "after" was always 0.

I don't think the before is much different, unless your water company change its water source periodically. We do that sometimes. 100-200ppm is a big range... are you sure your TDS meter is working fine?

 

[mling]

Yes I have a pressure gauge that is working fine. The "before" is 100 to 200ppm, today the "after" is in the 70's. The thing that confuses me is the it was working great for at least the first 2 to 3 weeks, don't even know what the "before" is since the "after" was always 0.

I don't think the before is much different, unless your water company change its water source periodically. We do that sometimes. 100-200ppm is a big range... are you sure your TDS meter is working fine?

140ppm was today''s tap ppm. I use the hand held TDS reader, that came with the typhoon, to get that reading.

The meter on the Typhoon has the "before" usually about 200. That was the case this morning, but when I came back from work this evening, it went well over 600. Flushed the unit and it fell to under 300.

 

[Ben1]

Well if before the membrane its 200 and after it is 70 your membrane is only rejecting like 65%, should be way higher then that. What is your pressure gauge reading, do you get enough PSI to work the unit properly?

 

[mling]

Well if before the membrane its 200 and after it is 70 your membrane is only rejecting like 65%, should be way higher then that. What is your pressure gauge reading, do you get enough PSI to work the unit properly?

Pressure gauge is 60 when the unit is off, gets to about 105 when I turn it on, to make water. There is a sign on the Typhoon that says High Pressure 75 psi. Could it be that the pressure I have is too high ?

 

[Anonymous]

I am confused. You say the TDS is 140 ppm with a handheld, but the meter on the filter says 200-600ppm for the same water? Why there are like 4X bigger reading?

Another thing is the pressure. You are talking about the pressure on the RO housing, or the pressure right after the carbon stage? When my unit (Spectra-Pure, 15+ yrs old) shuts off, the pressure gauge drop to zero since the gauge is on the RO housing. If yours is on the housing, and it stays at 60 psi, something is wrong.

If you pressure is too high, the rejection ratio will be lower. It can be simply fixed by installing a pressure regulator right in front of the filter, or if you your entire house pressure to go down, there is an existing regulator near where the water go into your house.

 

[Ben1]

I wish I lived in your house, my pressure is like 30 PSI and my showers suck....

 

[mling]

I am confused. You say the TDS is 140 ppm with a handheld, but the meter on the filter says 200-600ppm for the same water? Why there are like 4X bigger reading?

The 140ppm is the TDS of tap water using the handheld. I am asso confused as to why the filter TDS says it is much higher for the same water. From the responses I have received, looks like my membrane needs to be replaced. There is also the possibility of a faulty TDS meter. Maybe the hand held is not as reliable ?

 

[Anonymous]

Most of the TDS meters we use in the hobby are just not very good, period. I have a feeling that the one you have on your filter is a piece of work, due to the fact that the reading changes so much. This makes me believe part of your worry that the alarm going off is not justified. I would get hold of a better quality TDS meter before start replacing the membrane, or waste your water with flushing, or anything else.