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.
Step 1. Measure the size of your pond in gallons. This will determine the wattage of ultraviolet (UV) light that you need to effectively treat your pond. For ponds up to 400 gallons, you need a UV light with a minimum of eight watts. For ponds between 400 and 800 gallons, you need a 15-watt bulb, while ponds over 800 gallons require a 25-watt UV bulb. If your pond size is just at the edge of the recommended UV, use the next higher wattage.