Three methods that estimate the algal and nonalgal contributions to the total particulate matter light absorption were analyzed against the experimental Kishino method in a wide variety of environments. We found that one method gave better overall correlations and slopes closer to 1 than did the other methods, but the method overestimated the nonalgal fraction when the nonalgal absorption to total particulate matter absorption proportion in the sample was low. As a result, a correction is suggested and results are compared with those of the other methods, showing that the combined use of the original algorithm and the correction do configure a suitable basis for differentiating the algal and nonalgal fractions using as input only the total particulate light absorption data.