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.
Add pavers or large stones around the edges of the pond if you're using a flexible pond liner. This covers the liner edges and holds the liner in place. Add a dechlorinator liquid to the water, and then allow it to set for at least 24 hours before adding your koi. Spray paint or garden hose.