Is microsiemens the same as ppm

[aquagal]

I have a TDS meter that came with my RO unit that measures in ppm. Is the reading from the TDS meter (in ppm) a measure of hardness and is this the same as microsiemens? I ask this because there is a lot of reference to getting discus to breed in water that has a specific conductivity (in microsiemens).

Thanks.

Sherry

[bs6749]

The reading from the TDS does measure hardness of the water. What it's measuring is the number of ions in solution (ppm's), pretty much simple as that.

Microsiemens is a measure of the electrical conductivity of the solution. This conductivity is proportional to the amount of ions in solution. It is the ions afterall that carry the electrical current. If you had pure water, with absolutely nothing else in there (no salts, ions, etc.) there would be no electrical current.

So in short, they are not the same thing, but they are closely related.

[aquagal]

what type of meter does one use to measure microsiemens?

[Graham]

A TDS meter measures in microSiemens (uS) via conductivity. This is no different that a salinity meter. It measures the ability of the water to carry an electrical charge.

Drop a hand full of salt inand watch the numbers climb where as GH won't move

The hardness of water, expressed as GH is a measurement of mainly calcium and magnesium and is measured as Calcium Carbonate in most drop test kits

[bs6749]

Drop a hand full of salt inand watch the numbers climb where as GH won't move

Unless you added a handful of calcium and or magnesium salts : )

Thanks for covering the part I forgot to mention.

[geleen]

http://www.sensorex.com/support/education/conductivity_education.html

This may help.
J

[aquagal]

o.k., sorry if I'm being dense, but I'm still confused whether MY TDS meter (which says ppm) is giving me a meaningful reading (comparable to a reading in microsiemens)?

If my fish DO decide to breed, I know there is a preferred conductivity and I want to know what instrument to use to measure this?

Thanks
sherry

[tedsdiscus]

Hi Sherry,

First of all, I was just as confused as you were when I bought my TDS-3 from HM Digital. From my reading online, and trial and error, I found that I had the best success with a reading of about 50 ppm. Please don't take this as gospel, like I said, I don't know for sure. I think 50 ppm is about 80-100 uS from what I've read, I could be wrong, but my eggs are hatching fine with very little fungus eggs.

Hope this helps, and good luck with your pair.

Ted

[aquagal]

Thanks Ted...that's exactly what I was curious about...that's pretty low also. I could get it probably by doing 75% RO + 25% tap...I'll have to experiment. I assume that dropping the conductivity this low does induce spawning? My fish are still too young, but I want to be ready.

thanks again.

Sherry

[tedsdiscus]

Hi Sherry,
I don't think dropping the TDS does much to induce spawning, it's just to make the water right for the sperm to get into the eggs and for the eggs to hatch. At least that's what all my reading tells me.

Good luck,

Ted