I have been using a gallon jug to premix my nutrients and set my PH levels before I pour it in the NIWA. This makes it much easier and is just the right amount for a full nutrient change out. I have also picked up a turkey baster at the Dollar Tree that I use to pull samples for PH testing. It has also been very handy.
How were the results of your growing adjusting the levels, how are you measuring the levels?
Proper PH is circuital for good nutrient uptake. I have targeted PH6. I'm using a General Hydroponics PH up and down kit that comes with the test tube and reagent. I wanted to go with the Fox Farms Gringo PH liquids to keep the natural theme I have going but the cost of the G.H. was enough to swing me. I'll make sure to flush before harvest anyway.
So we assume you are mixing your own formula based on nutrient manufacture indications, may we ask what are you growing?