acceptable 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

[cnaegler]

<a href=showthread.php?s=&postid=15123165#post15123165 target=_blank>Originally posted</a> by 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

The whole county flushing thing could have ruined your filters. To be honest, if my TDS is more than 0, i change my filters. Any more than 1-3 ppm , IMO, is too much for our tanks.

[iFisch]

Well, it depends on how hard the water is, before coming and going through RODI.

Since our water here in FL is really hard, a TDS reading of 1-2 is normal. Out of about 20 LFS's I've been to, its been 1-4 TDS. Never seen "0" TDS here. Only way to achieve that, would be to get a water softener first, then run that through RODI.

[cnaegler]

I live up here in the Great Smoky mountains where the well water is pretty much the spring water you fine fellows buy at the store, so mine is 27 before any filtering and 0 after. :D

[BigJay]

<a href=showthread.php?s=&postid=15123906#post15123906 target=_blank>Originally posted</a> by iFisch
Well, it depends on how hard the water is, before coming and going through RODI.

Since our water here in FL is really hard, a TDS reading of 1-2 is normal. Out of about 20 LFS's I've been to, its been 1-4 TDS. Never seen "0" TDS here. Only way to achieve that, would be to get a water softener first, then run that through RODI.

Same here, I usually don't stress having 1-2 TDS. It seems silly to worry about it when I get 2-3 TDS just by putting my RO/DI water in a big plastic trash bin.

An no, my tank is not taken over by algae.

[mling]

For where I am in Fairfax county, N. Virginia, just outside of Wash DC, the water is in the 100 to 200ppm range. 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" was since the "after" was always 0.

So if the county water flushing ruins the RO/DI system, what do most of you do during such events ?

[Jerm77]

I have 400-500 tds before my RO. its a very large system 1400gpd RO. I don't know about your local flushing program. are your filters sitting out of sunlight? does your RO usit sit several days before you demand more water?

[jjw2121]

My well water is at ~ 750 before and about 7ish after.

[mling]

My RO system is in a bath tub so it never sees sunlight. While it has a float valve, I have yet to use it. I just fill 160G Instant Ocean tubs and manually carry them to another location where I mix the salt and then store it.

I use my RO probably once a week for top off. Alot more during water changes since I do have a total of about 250Gal.

Does it matter that a RO system sits unused for a long time, like 2 weeks ?

[Jerm77]

water sitting in the RO system for a couple of weeks can cause a slight output tds spike, after running for a minute or so it should stabilize.

excess co2 in water supply can damage the DI. have you verified if the DI
is working? it could be exhausted. read below to determine if its out.have
you tested TDS before the membrane and after the membrane? have you
tested the TDS after the membrane and after the DI, or before and after
the DI? but, 50ppm after the membrane seems like the membrane is at
fault.

are you getting the proper amount of flow?
what is your RO to waste ratio?

from air water air website:
Membranes are rated at 77 degrees temperature and 50 PSI.

For every pound of pressure less than 50 subtract 2% of the output.
Example 40 PSI subtract 20% of the 75 for 60GPD

For every degree below (77) you lose production. Subtract 1.4% per
degree lower than 77. Example 57 degree water is 20 degrees less than
optimum. 20 x 1.25 = 25% less production. So a fifty GPD membrane will
only produce 75% or about 37 gallons

The major difference is in the rejection rate and the life of your DI
cartridge. All of our reefkeeping systems are designed to make -0- tds
water. The 75 gallon per day membrane is rated to reject about 98% of
the TDS. The 100 GPD Membranes is rated at about 90%. That difference
changes the amount of work the DI has to do. If you do not need the
large volume of water you are better off with the 75 gallon per day or
smaller membrane. The non rejected TDS is mopped up by the DI so the
less mopping up to do, the longer the DI lasts. Our DI cartridge is rated at
6,800 PPM Divide the 6,800 by the output of the membrane to
guesstimate the number of gallons you can expect from the DI.

Example: Tap water 200PPM. The expected output of the 75 gpd would be
6-12 ppm. The expected output of the 100 gpm would be 20-40 ppm.
Actual values are dependent on you tap water quality, pressure and
temperature. 6800 > 12 = 566 gallons 6800 > 40 = 170 gallons.