I've been using the TF100 kit once a week to get a full set of results, and using my basic color matching test kit from Leslie's during the week just to see the FC and pH in the evenings.
But today was the first time I tested FC using both kits, out of curiosity. The color matching test showed a FC level of about 4. But when I tested using the TF100 kit, I got a FC level of 9.5! I tested both within a few minutes of each other, while the pump was running.
Has anyone gotten vastly different FC results using different test kits? And does the color matching test tend to give lower numbers?