Neptune's years are 164.8 Earth years. Its days are 16 hours and 6.7 minutes long. Although Neptune's days are shorter than our days, its years are still longer than ours.
Most colorants will last in your pond approximately 30 days. You may have to add more pond dye before 30 days if you have execissive rainfall, run-off, a heavy out flow, or evaporation. If your colorant is fading you will visually be able to tell and should add more dye to the water.
Permanent hair dye lasts up to eight weeks. A hair dyeing kit. Semi-permanent hair dye cannot be used to lighten hair. Henna can be used to make a semi-permanent hair dye. Semi-permanent hair color lasts about six weeks or up to about 24 shampoos. When dying hair, it's recommended to wear gloves to prevent staining the hands.