Another PH question

[abyrd]

my water tests have a test for PH and also a high range PH test. On the high range it gives me a reading of 8.0 on the regular ph test it gives me a 7.6. Any ideas on why the two read differently and which one should i trust?

[emc7]

Are both test results in the middle of the scale? The far end points of any test are almost always less trustworthy than the middle ones. The only sure way to know which is correct is to buy a standard solution of known pH and test the test. I have to say that a pH difference of .5 may be "within experimental error" for a liquid test. Its likely that your real pH is 7.8 and the accuracy is + or - .2 or even .4. Check the manufacturers literature for promised acuracy. This is a freshwater tank, right? To say your water has pH of 7.6-8 is good enough for choosing fish and keeping track of. The absolute pH is less important that its fluxuations. I really don't recommend pH adjustment for beginners, just choose alkaline favoring fish and plants. If you really want accurate numbers, you can buy an electronic meter and calibration solutions.

[abyrd]

well I was told on another post that my numbers were okay. I just couldn't figure out why I was getting different readings. On the regular PH test the 7.6 is the last one on the card.... on the high range test its the second one down (it starts with 7.8).

[emc7]

If 7.6 is the last one, than a reading of 7.6 is really > or = 7.6 so the high range test result is correct.