Tds Meter Readings

[asmodeus]

ok just bought a TDS meter for my RO/DI 100 GPD and my readings for
IN water is 470
AND OUT IS 170

Should i change my DI and a filter.

last date for DI changed is JAN /30/05
CARBON MAY 08/05
2 pre fiters 1 MIRCON EACH first one jul 17/05 just changed
other filter 1 mircon june 30/05


mike

[Entropy]

Do you have RO, or just DI? If you have RO, your RO membrane is shot. If not, your DI is used up, and you need to either renew it, or replace it. I suggest a good RO setup if you don't already have one.

[Entropy]

You should be reading about 20ppm out with a good RO setup, and zero after the DI. I have very similar water quality (470+ ppm) and my 50gpd RO puts out 17ppm water.

[asmodeus]

ok i see i will change my Di and yes i have a RO with DI unit and i will check the the membrane too i have a old one if i have too i will get another one.

[dustin Combs]

time to refill the di resin

[asmodeus]

UP DATE

CHecked the DI and it was Orange or there was only about 1" left that was black. Changed the DI and OMG


TDS READING 000 PPM

thanks for the answers dustin and ENTROPY


mike

[Mekong]

Whats the reading out of the RO, if its over 20 you might be putting so much stress on the DI that it will be exhausted really quickly.

You could just use a DI filter and get 0 but it would last 20x less. The RO and prefilters make the DI last longer.

[AZDesertRat]

Definitely check you RO only product water. It sounds like your RO membrane is bad. If I might make a suggestion here, replace it with a 75 GPD Dow Filmtec membrane rather than whatever 100GPD membrane you presently have. Dows 75 GPD will give you 98% rejection at 50 psi. Other membranes will either give you 90% rejection or it will require 65 psi to produce the water or both. Watch out for sales pitches like " Genuine Dow Material". Other suppliers use Dow materials but it takes 65 psi rather than Dows 50 psi to produce the same amount of water.

I use a Dow Filmtec 1812-75 75 GPD membrane, my tap water averages 550 to 600 and reaches 800 TDS at times and my RO only product water averages 13 TDS. I have a large capacity vertical refillable DI filter that holds 24 oz of resin and it lasts about 200 gallons before my TDS starts to get over 2 or 3 where I change it out.
I think you will find your DI is only going to last 15 to 30 gallons at most if your TDS is in the 170 range. 12 oz of normal resin will adsorb about 3000 total TDS, 3000 divided by 170= 17.64 gallons.

[asmodeus]

ok i have a Question reference to the Membrane.

Can i hook up the TDS meter in put to plug in to the OUT MEMBRANE and have the OUTPUT going to the out water from the DI filter. Then i can keep an eye on both by a flick of the switch..

i have a generic 100 GPD RO/DI unit

[AZDesertRat]

I don't know why not. I use a handheld meter as I find it is easy to use and to check calibration without having to disconnect it from anything. They are only $25 most places and are a good investment.

[asmodeus]

ok then will hook it up tomoorw and keep ya informed man.

thanks for the input


mike :smokin:

[stank]

My tap water unfiltered is 52 ppm and 80psi, after r/o d/i I get 1 ppm. I guess were pretty lucky in AA county Maryland.

[Entropy]

Originally posted by reef'r
I guess were pretty lucky in AA county Maryland.


The weather channels says it is 82F and 80% humidity in Maryland right now at 11pm at night. Not that lucky... :p

[AZDesertRat]

You lucky dog! Actually with RO only you should get 1 TDS. With 98% rejection you should see 1.04 before the DI. DI will last you forever with water like that, actually about 3000 gallons per 16 oz of resin..