I have the TF100 test kit and have been using it now for about 6 weeks. Here's my current readings..
PH: 7.3 (using the Taylor K-1000 blue kit that comes with the TF100)
I also have a PH probe on my Rolachem, currently reading 7.5.
I would like to calibrate the PH probe, so I thought I would also test the PH using my old test kit, (a locally supplied Australian kit) for comparison purposes.
My old test kit read 7.7. The interesting thing is that the old kit requires that you add 1 drop of chlorine neutralizer before adding the 5 drops of dark pink PH reagent. (I read elsewhere on this forum that the better PH kits use chlorine neutralizer... Interestingly, the Taylor K-1000 does not)
So, I thought I would experiment further. I put on my put lab coat and protective glasses and did the following:
(1) Use the K-1000 test kit, but add one drop of the chlorine neutraliser from the old kit before adding the 5 drops of reagent. Result: PH = 7.7
(2) Use the old kit, but don't add the chlorine neutraliser. Result: PH = 7.3
So, in summary, both kits give the same reading with and without chlorine neutralizer! (7.3 vs 7.7)
So, question is which reading do I trust? How much affect does chlorine normally have on PH readings? (My FC is currently high at 10). I thought high FC tends to increase PH readings!
I realize that most people here will say "trust the Taylor K-1000 - 7.3 is correct". And I would tend to agree...
My old test kit has reagents that are almost 2 years old. Is it likely that the chlorine neutralizer has gone "off" and is raising the PH reading?