The first thing I did was let it dose at full speed for a day into seperate containers to see how close the volume was for each channel. If one channel is significantly less volume than the other, you might want to trim a tiny bit of the flexible tubing off, which causes it to be tighter against the drive wheels and will increase that channel's output slightly. Once you have the channels putting out approx. the same volume, you can start playing with the rate to get the volume you need - still with water. I spent about a week doing this stuff, I wasn't in a hurry about it.
So after I started dosing with the pump, I still wanted to test it every few days for a while to make sure I had the volume right, and I did have to tweak it a little but it's working really well now.
I changed mine - it was dosing 24/7 but now I have it dosing from 11 PM to 11 AM. I want to try to offset the PH swing a little, my PH can use a boost overnight... I'm not sure how much difference it is making but I think it must be helping a little at least.