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.
How does Bigen Powder compare with semi-permanent colors? Bigen Powder and semi-permanent colors are crucially different with regard to lasting color. Bigen Powder lasts about 4 to 6 weeks, while semi-permanent colors last about 2 to 3 weeks, washing out gradually. All permanent hair colors, including Bigen Powder, require a preliminary skin allergy test before each use. Your body constitution and condition change every day.