What's your TDS Reading? Mine is...

[EmilyB]

Okay....

The water goes in and through the first two stages before it goes into the membrane. Then it goes out from the membrane into the DI.

If I were to remove the DI to measure the output from the RO membrane, would not the condition of the first two filters affect this ?

Maybe I am missing something here. Thanks for your patience :wink:

 

[gman2]

Well that was toooooooooo easy. I thought it was going to be some complex calculation or something. Thanks for the simple explanation.

Tony

 

[reefland]

BTW, Rich intended to say 5 / 320 * 100 = 1.56 for the above example.

Doh!

Gman2, said another way that might be easier to follow:
If you had 320ppm at the input and 5ppm at the output, the membrane rejected 315ppm (320ppm - 5ppm). If you devide what you rejected (315ppm) by your original total (320 ppm) that indicates what percentage (in decimal form) that the membrane rejected. 315 / 320 = 0.984. You can then multiply the last number by 100 to express it in percent as Rich showed above to get 98.4%.

Much simpler. Now that I think about that was exactly how I figured it out the first time.

 

[EmilyB]

Okay....

The water goes in and through the first two stages before it goes into the membrane. Then it goes out from the membrane into the DI.

If I were to remove the DI to measure the output from the RO membrane, would not the condition of the first two filters affect this ?

Maybe I am missing something here. Thanks for your patience :wink:

Thanks for your help with this Rich........ :roll:

 

[SPC]

:roll:
Steve

 

[Anonymous]

The prefilters do not have anything at all to do with the removal of TDS.
The prefilters are bodyguards for the rest of the system. The sediment filter which is based on micron size removes the particulates from the water that would otherwise very quickly clogg the carbon block. The carbon block removes a small amount of the residual particulates and more importantly removes the chlorine from the water that would otherwise destroy the membrane. The TDS doesnt begin to be removed at any decent rate until you reach the RO membrane....
Remember that TDS and particulates are 2 different things and TDS can not be guaged by micron rating because TDS is typicaly molecular and much smaller than particulate.

I stole the above from a thred over at ReefCentral from Bryan at Aquatic reef Systems.

So using a TDS meter before the membrane will not show you much.

 

[andrejka]

Does anyone know how TDS compares with conductivity values? I don't have a TDS meter but have an access to a conductivity meter. My tap water is 370 microSiemens, for example, and water after DI is 0 microSiemens.

 

[andrejka]

Does anyone know how TDS compares with conductivity values? I don't have a TDS meter but have an access to a conductivity meter. My tap water is 370 microSiemens, for example, and water after DI is 0 microSiemens.

 

[EmilyB]

Thanks JDM (and Steve for the bump :lol: )

I just got my TDS meter today and can't wait to try it !

 

[gman2]

Does salt water have a specific or ideal TDS reading. This TDS stuff is new to me.

Thanks
Tony

 

[reefland]

Nah, not really. Specific Gravity (SG) or Parts Per Thousand (PPT) are typically used to describe salt water.

 

[ChrisRD]

Does salt water have a specific or ideal TDS reading. This TDS stuff is new to me.

It would be a HUGE number. I can't even get a reading on my meter - it's off the scale -

 

[AJT]

I have a couple of questions about the dual TDS Meter.
How does it hook up to Ro/DI filter, is it in line or do you have to hook it up each time to check?
Do you have to calibrate the probes?
Do you have to probes after a certain time period?
Can the unit be put outside?
Is it better in your opinion than a hand held model?

Thanks
Andy

 

[reefland]

I have a couple of questions about the dual TDS Meter.
How does it hook up to Ro/DI filter, is it in line or do you have to hook it up each time to check?

It is hooked up inline. Mine came with all the fittings needed. You replace the elbows fittings your system currently has with a few Tee fittings.

Do you have to calibrate the probes?

Dunno, I haven't. I'm not really concerned if my DI output is 3ppm or 4ppm. Anything over 0ppm I change my DI. It seems to be in sync with the typical push button water testers common to many RO/DI units. When mine shows 1ppm, they show a red light (depends on what level you configure the device for of course).

Do you have to probes after a certain time period?

I doubt it. Heck, not even sure how to change its battery. :wink: I have no idea if the probes get replaced. Haven't had it long enough to worry about.

Can the unit be put outside?

huh?

Is it better in your opinion than a hand held model?

I like it better. Hand held gets stuffed someplace and you never find it when you need it. I had a Hanna hand held unit, I gave that to another reefer.

 

[AJT]

Thanks for the reply.
My Ro/DI unit is outside by my water faucet. I was wondering where the readout is placed, or do you hook it up each time you use it??

Andy

 

[reefland]

You would not disconnet the unit I have. It gets attached to the RO/DI unit with some sticky velcro.