PH confused

[xander]

I tested my water using both tetratest and aquarium pharmaceuticals. The tetratest reads at about 7.5. The A.P. test reads 6.6. This is the same water and these tests are new. I don't get it. I wonder which is the true reading. :x this is very frustrating.

 

[Electrobes]

Did you test it in a new tank where the pH may have just been added? Is the water fully cycled? Plus test strips are not very reliable.. I have never found them to be, nor the test tube ones. usually whatever it reads is typically lower than what you actually have. 6.6 sound spretty low, and 7.5 sounds pretty high if you've done nothing to your tank pH wise. What pH adding method do you use.. those tablet fizz ones... the powder kind.. etc?

 

[xander]

I am using test methods that are not strips. the tetratest uses a liquid with isopropanol and call for 7 drops in 5cc of water. the Aquarium Pharmaceuticals use 3 drops in 5 cc of water. this is not from a new tank. I have used nothing to alter the makeup of this water. When I did my first major water change when I moved I added some ph stable which is a neutral range buffer. this is a powder and I didn't add nearly what the directions call for. just a sprinkle really.

 

[TankGirl]

Check the dates on the bottles, as one of them might have been sitting at the LFS for a while. I trust the AP tests, and you can check the date of manufacture by looking at the last digits of the lot number. AP says they are good for about a year after the manuf. date. Unless you are breeding a tricky fish, I would get one test and stick with it, because even if the exact number is off, you can spot a change, which is really the danger associated with pH. As long as the number remains the same you can assume your pH is stable. I am getting an electronic pH monitor (http://www.aquabid.com/cgi-bin/auction/auction.cgi?testkits&1068404406) and I am going to compare the results of this monitor with the AP test kit.

 

[Sinuhe]

What is the pH range for the Tetratest one? For the AP one it's probably something like 6,0-7,6 right? I use the AP High Range pH test, since my number are always around 7,8-8,0.