BASF 59013424 1 gal Black Onyx Lake and Pond Colorant. Black Onyx lake and pond colorant creates a dark, reflective look in decorative lakes and ponds for a stunning appearance. With both liquid and WSP (water soluble packet) formulations, Black Onyx colorant is convenient for every water feature. Apply liquid directly from the container, near the shoreline. Our unique WSP is a highly concentrated, premeasured, dry formula that disperses evenly as it dissolves in the water body. Use Black Onyx colorant in conjunction with Lake Pak WSP biological clarifier for an effective nutrient management and water clarity improvement program.