Crystalpro / Aqua Black Tropical Water Conditioner Black water concentrate additive for tropical aquariums. Darkens the water and creates natural tropical aquarium conditions with naturally sourced humic acd, tanins from oak tree extract and active iodine content that keeps fish healthy. Does not affect pH. Use Crystalpro pH Minus to lower pH. Instructions: Add 10 to 20 milliliters to 100 liters. Add 40 ml maximum to 100 liters to achieve darker water color. Approximately 15 drops is 1ml, a bottle cap is 7ml. 125ml is enough for 1.250 Liters. Safe for all freshwater aquarium creatures. Cautions: Keep out of reach of children. Not for human consumption. In case of contact with eyes or skin, rinse with plenty of water. Keep it cool. Do not freeze. Shake the bottle well before use. Do not overdose. In this case, change the water.