I tested both of these products separately over the course of two, three-month periods.

Koral color: keeping my parameters the same as usual (same food, lighting, etc.) the only addition I made was adding Koral Color to my regular regiment twice a week (as specified on the bottle).
Results: the product brought out some color on a few corals, but the difference is somewhat subtle. It seemed to encourage the appearance of more reds and blues but it didn’t enhance any other colors.

After the first trial over the course of a three-month period, I took a month break from both products to establish a new baseline. Then I began dosing Fuel into my weekly regiment with the same conditions as outlined above.

Fuel: immediately, I was pleased to find that the cap for this product has measurements for dosing. After the first month I began to notice certain acans showing a different color. Namely, more greens and whites latent within the coral began to appear. Towards the end of the three-month period, other colors began sharpening as well. Overall, Fuel was very appealing to me as it not only served to enhance colors but also served as an additional food source for my corals.

In conclusion, both products are effective in bringing out colors, but I found Fuel to be much more appealing as I was able to produce healthier and brighter colors at the end of my testing period.