Proper way to test for pH?

Misomie

I tested my water myself and got something below 7.4 (the cards don't go lower). I had a store test it and they got 8.0ish. This left me really confused. :K (both are liquid test kits)

Is there some special care I should do/take to get an accurate reading? I'm going to test a hypothesis of mine by testing the tap, pH of the 20, and pH of the 75.

If my tank really is at 8, it is fine for my current fish but pushing it so I'll add driftwood to fight it. :P

On other news, I've had two practice tests for a test in my AP Bio class that would allow me to receive college credits. Some of the questions weren't covered, but two of these related to knowledge I gained because of my fish. X3 One was on characteristics of fast flowing streams while the other involved ammonia and the other forms of nitrogen. SCORE! XD

Tazman

What test kit are you using?

Misomie

API Master Test kit. (The good ones, though mine was designed for marine tanks, but I don't think it'll cause such a result change.) Although I did handle the water samples differently and my tank was an ex-marine tank so it could possibly have altered the pH. Hm. (That's why I want the other test groups)

Tazman

The color charts for Marine tests are different from the Freshwater tests.

You can download or reference the Freshwater charts here. The low range pH is the same but the high Range chart is NOT.

What do you mean by "handled the samples differently" it is the same as you would testing a Marine tank. The instructions are exactly the same for all the tests.

Misomie

Ah, ok. I'll re-check it in a few hours. (and the others as well)

Well, on the one I tested, I just tested it according to the instructions. On the other I shook it up first as you would if testing sink water. ^^;