Change colors based on values of other cells

Hello, I need some help with excel. 

Below are images of the worksheet template I use. For every project, I start with a blank template and then input different values based on my testing, as can be seen in the second and third images. The initial RETAIN sample is the baseline for the project and how much deviation there is from it, gives us an idea of how the product is coming along. Basically, I want to be able to set up a formula on the template, so that whenever I reuse it, if one project's pH is 5.0 and the viscosity is 24,000, but another has a pH of 8.5 and a visc of 80,000, that the values and I input in the subsequent months change colors going off the RETAIN samples.

So for pH, using 4.0 as an example, if it goes under 3.0 or above 5.0, I want it to change colors, but if I reuse the template for a different project and the pH is 7.5 instead, I want it to change colors if it goes under 6.5 and above 8.5. Conversely for viscosity, if the RETAIN is 50,000, I want it to change colors if it goes under 40,000 or above 60,000.

Is any of this possible? What do I have to do in order to input these formulas into the template so that it's automatic from now on?

Also, my experience with Excel is only with the basics, I apologize if I don't fully grasp the answers to my question right away.