pH, pH, pH pHooey! :)

[djlen]

Roan -
Don't waste your money on a tester. Just know your kH and test your pH, then compare the two on a chart or calculator to learn your CO2/ppm.

Len

 

[sardesign]

djlen,

Here is a question... since "things" in tap water can affect KH tests. Is it safe to theorize how high the KH is?

I.E.

my tap is PH 7.0 + KH 7.0
I would "theorize" that my KH is 4 units high because of phosphate (or something else) so I would need a KH of 12 or 13 to get it accurate?

the CO2 charts definetly cannot be used with this situation because there is NO way that I have 20+ CO2 in my tap water. Any suggestions?

 

[daveedka]

djlen,

Here is a question... since "things" in tap water can affect KH tests. Is it safe to theorize how high the KH is?

I.E.

my tap is PH 7.0 + KH 7.0
I would "theorize" that my KH is 4 units high because of phosphate (or something else) so I would need a KH of 12 or 13 to get it accurate?

the CO2 charts definetly cannot be used with this situation because there is NO way that I have 20+ CO2 in my tap water. Any suggestions?

I'm not len, nor do I pretend to know as much as Len or Happychem either one, but there are a couple of thoughts to consider.

First is that if you use chuck Gadds charts it specifically states that it is negated unless carbonate is the buffer. discalimers are only handy if you know your buffer, but water companies usually will tell you the chemistry they send down your pipes.

Next thing is are the numbers you listed straight from tap or tested after gassing off for a good period. More often than not tap water and some well water are in fact very high Co2. 20 ppm co2 would seem very normal to me. Water companies in a lot of cases force the water to neutral with co2 simply because it helps reduce lime build-up in the pipes. My tap water comes out of the faucet at 6.8-7.0 ph. it equalizes at 7.6-7.8 with a Kh of 2-3 and 1 ppm phosphate. it hits pretty close to the Ph charts.
Dave

 

[happychem]

sar,
Every 1 ppm of PO4 only increases KH by 0.5 ppm. My Hagen test kit measures KH in 10 ppm increments, so unless I had 20 ppm PO4 in my water, PO4 is not going to have a significant effect on KH.

Borates may be a concern for folks who like in the central states - I think that Borate is found there, been a while - but elements such as PO4 (silicate would be another) are so heavy compared with carbonate and found in such low abundances that they don't have a significant impact on alkalinity.