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.
This will allow it to cover the seams easier. Pond Armor is going to have a gloss finish where as CIM at first has a gloss finish that after 6 months turns to a flat finish. Both are easy to use and apply but you do have to work fast. Both will stick to the vertical walls with no problem. Pond Armor comes in different colors and clear where CIM is black only.