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How hard *is* his water?

> So I called Kent, and was told that "Medium hard" means 210 ppm, and that
> 100 ppm is one degree of GH.  They also told me that the hardness test kits
> typically will not show most of that because they do not measure all of the
> GH contributing chemicals in ROR.

I don't know what they're saying.  210 ppm hardness as CaCO3 (about 12
degrees) might be regarded as "Medium Hard", but I don't know of any
system of units where 100 ppm is one degree.  Usually you'll see 17.9 (or
17.8) mg/l as CaCO3 is 1 degree. 

The idea that test kits won't show all the hardness they add is odd.  I 
wouldn't believe it without knowing *what* it is they add that generates 
the "stealth" hardness.  Is it possible that they are using something 
that dissolves rather slowly, and that the hardness will increase over 
time as that part of the ROR dissolves? 

> My meter reports 680 uS on this tank.  Kent says to multiply by .8 for
> numbers in this range to get 544 ppm tds.  Dividing by 200 and multiplying
> by 11 I calculate that I've got a hardness of just under 30 in my soft
> water tank.  I don't even want to *think* about my hard water tank.

Huh?  I don't see where the values of 200 and 11 came from.  0.8 is a little
high for most water.  The published range I've seen for natural water is
0.57 to 0.75.  For most potable waters the value tends to be close to 0.6. 
Values over 0.75 are possible but probably require an unusual content of
nonionic solutes. 

> Help!
> How do I get this under control when I can't (apparently) even get a
> measurement on what is there now?  According to the AP test I need to add
> hardness.  According to the KM's interpretation of my conductivity test I'd
> better start doing water changes pronto.
> What now?

I'd put my trust in a good hardness test kit - or in consistent results
from 2 kits.  But I'd also wait a while and see if the hardness might rise
because of slowly dissolving chemicals.  Before adding anything else I'd
check other parameters - alkalinity in particular - to make sure that
other things are staying in bounds. 

> Frustrated in Ottawa.

Roger Miller