Hardness Scales

maelstroem · Post by **maelstroem** » 01 Jun 2003, 20:28

Hi

I`ve just bought one of Hanna`s pocket meters.
It measures Ph - Temp - EC/TDS.

What does the EC/TDS stand for.

When I tested my tank water the Ph was 6.66 . The EC- (it shows as uS on the meter) measured 363 and TDS as 182.

How do I convert EC/TDS to degrees hardness in UK Clark-German Deg- US degrees.

Can anyone throw any light on the above for me.

Also how does one lower the hardness without affecting the Ph if this is possible.
I would like to get the hardness down to below 100ppm while keeping the Ph at around
6.5 - 6.7 . I have an RO system but when this water is added it obviously lowers the hardness but also drags the Ph down with it.

Thanks

Post by **Silurus** » 01 Jun 2003, 20:41

Electrical Conductivity (EC), Specific Conductance - simply defined this is a measure of a solution's ability to conduct electricity. Usually measured in Siemens/meter (S/m).
Total Dissolved Solids (TDS) - this is a measure of the salts dissolved in water. Generally speaking the TDS in mg/L is about 2/3-3/4 of the EC measured in uS/cm.
There is no method of directly converting EC/TDS into gH/dH, but there are some rough approximations. Here is a better explanation.

maelstroem · Post by **maelstroem** » 01 Jun 2003, 21:18

Thanks Silurus the link was informative too.

Is there a general table like 0-50ppm very soft. 51-100 soft etc.

Can you help me at all with the second part of my post re lowering hardness w/o affexting Ph

Thanks again

Post by **Silurus** » 01 Jun 2003, 21:58

Is there a general table like 0-50ppm very soft. 51-100 soft etc.

Try this.
As for lowering hardness without affecting pH, it depends a great deal on the quality of your water. Generally speaking, it's difficult to make water softer without affecting the pH as softening the water tends to lower its buffering capacity.