Oh man, that reminds me of my old wireless keyboard that would just freeze up. Took me forever to realize it was the receiver being too close to a power strip.

Your "eyeballing" must mean using the whole bag!

Did you ever consider coolant recycling just a hassle? I used to see it that way... thought it was too much effort for little gain. But then I saw how much money we were throwing away with new coolant every time. Plus, the idea of contaminating local water started to bother me more. Setting up a simple filter system made all the difference, just like you said. Now it feels wrong to even think about dumping it out back.