Printable View
I've seen this question posed before, but didn't read the replies because it didn't interest me at the time..lol. It must have been lost in the archives. I have come to realize that I am an idiot when it comes to determining precisely what color is closest to my sample. I would love an easier (more accurate than my poor eyes) method if available.
TIA!
There may be a titration method for pH, but I'm not sure. I've got a Hanna pHep 2 probe with temp correction that works great, but it really don't use it that much. I found that the accuracy of the phenol red is plenty close enough for my pool. Maybe if I was doing some "emergency green pool" fixes, I might use it, mainly because many of those pools might be out of the range of a phenol test. Heh, I should put mine up for sale.
Michael
There is no easy titration method to determine pH. pH meters will work fine IF you calibrate them with freshly mixed standards and the probes are pretty easy to break and have to be store wet. If you don't take the time to calibrate them they are useless. IMHO, more bother than they are worth! (I have experience with them but have NEVER used one in a pool!) Phenol red is easy and accurate. For a 'quick and dirty' test (as far as pool water is concerned)--If it's orange to yellow it's acidic, if it's purplish it's alkaline and if it's red to reddish orange it's pretty much where we want it to be for a pool ( I know this is a bit of an oversimplification but it is 'in the ballpark')
A good way to familierize yourself with the colors of the indicator is to take a vial of plain water and add your phenol red. now add something alkaline like the tiniest pinch of borax and note the color (purple), Now add vinegar drop by drop and look at it change color until it is yellowish orange and note the corresponding pH readings for the color change.
do this once or twice and you will 'learn' what the different readings look like and it will be much easier!
I have found that some cheap (and not so cheap) comparator blocks for pH (usually a pH/OTO duo) have TERRIBLE color standards that do NOT match up to the indicator colors ( the comparator in my Walmart test kit is an example of this--I have NEVER seen phenol red come close to the color of orange they have for 7.2!) The ones from Taylor, LaMotte, and of course Ben do not have this problem.
Even with these "bad" comparators you can still learn what color the indicator is at a given pH by my suggestion of going through 'all the colors' and matching them up.
If you happen to have one of the Taylor test kits with the acid demand and base demand reagents it is even easier (and a better use for these reagents than those acid and base demand tests!:rolleyes:) Just put the indicator in the water and add the base demand drop by drop until the color matches 8.2 and then add the acid demand drop by drop and you will see all the colors and the pH they correspond to.
Bottom line is this, If you take a bit of time and get familiar with your test kit it will make your testing easier and your results will be more accurate.
Hope you find this useful.