PH, how does it work???

[MaryJaneMonkey]

Okay, so I'm using 18gal rubbermaids, and when I add the first teaspoon or two, the ph hardly drops, but when I get into the 6 range, if I add 1/2 a tsp the whole tub drops to like a ph of 4. I understand that the ph scale is a power of ten function, so....how do you get your ph just right?

Any tips, hints, would be great.
Thanks for helping out a new member :)

[michaelpeg]

maybe after adding the first teaspoon let it sit and mix for a while before testing? not sure but that is wierd

[MaryJaneMonkey]

I think I got it...
well, since the pH of 6.0 is 10 times more acidic than 5.0, it takes 10x less *ph up, down etc ) to go from 6 to 5 than from 7 to 6.
So it takes 100x less to go from 5 to 4 than from 7 to 6.

[michaelpeg]

really? hmm i didnt know that, cool i guess you taught me something.

[stinkyattic]

when I add the first teaspoon or two, the ph hardly drops, but when I get into the 6 range, if I add 1/2 a tsp the whole tub drops to like a ph of 4.You have discovered the concept of buffering range.

CaCO3 has a buffering range in the mid 6's and can take plenty of acid to drop it out of that range, but when the CaCO3 has all been used up in the neutralizing reaction, pH plummets.

This is used to determine 'alkalinity' of surface waters by measuring the start pH, then taking the pH down to 4.5 with H2SO4 and then EXACTLY measuring the amount of H2SO4 needed to take a given volume of the water down to pH 4.2.

It is also the concept that allows surface waters to retain a pH that is hospitable to plants and fish, even in the presence of acid rain, as long as there is ample limestone in the substrate or dissolved in the feeder brooks.

[sensilights]

so in reverse would it take 10x more to go from 6.0 to 7.0, than it would to go from 5.0 to 6.0?