 You're going to be using a CBL and a calculator. So the first thing you need to do is to connect the CBL and the calculator with a link cable. And then you need to find your pH probe and plug that into channel one at the top of the CBL. You need a standard four and seven or four and ten to do the calibration. So the first thing you want to do is to go to programs or apps wherever you've stored your program and you want to find a program called Kimbio. So you can either press three and enter or arrow down. Once you see the commercial press enter, now you have a menu that says set up probes. So what we're going to do here is we're going to tell the CBL and the calculator what probe we have plugged in there. So we're going to press enter to set up probes and it asks us how many probes we're using and we're using one so we'll press one and enter and then it says what kind of probe and we're using a pH probe so we're going to select pH probe and it says where did you put it? So remember we put it in channel one so we're going to press one and enter and what we want to do is we want to perform a new and you should always perform a new calibration with a pH probe because they don't hold those calibrations very well because it's such a sensitive instrument. So let's perform a new and so it says let's wait 30 seconds for the electronics to warm up so we're going to wait 30 seconds and then press enter. What we do next is we take our pH probe from our storage bottle and these are stored in a solution so that it protects the probe. The sensitive part is right on the very tip. We're going to leave the cap and you see there's an O ring right there we're going to leave that attached if it's in the way we're just going to push it up a little bit but you leave it there because we're going to return it back to our bottle. So the first thing you do after you take it out is you rinse it make sure it you got the solution off and then we're going to put it in a pH of a known buffer that has a pH of four and you don't have to dry it that drop of water is okay. You put it here now watch what happens to your CBL so you see that the voltage and that's what it's reading is a voltage is changing but now it's staying constant when it stays constant we want to press trigger okay and if you notice on the CBL it says enter the reference point so where it says enter the reference point since we were using a pH of four we want to type in four and press enter so it's saving that number of that voltage and converting it to a pH now we're going to rinse our probe again and we're going to place it in a pH of seven watch what happens to the voltage okay it starts to drop okay and that's holding steady when it holds steady oops it changed again when it stays steady then press trigger when you press trigger it says enter your reference number and here we're using a pH of seven so we're going to type in seven and press enter so here on the screen you see slope and why intercept write these down in your notebook because if something happens during your experiment you don't have to perform it all over again you can input the slope and intercept and your calculator okay so now we have calibrated when we press enter it's going to return us back to the menu and we can now begin to collect data now you know how to calibrate a CBL pH probe