Laguna Fertilizer Pond Spikes supply important nutrition to aquatic plants for a period of one year. The temperature-activated feeding sticks release nutrients only when plants need them most--at or above 50 degrees F or 10 degrees C. Once activated, the spikes slowly release a well-balanced feeding formula that maximizes the size & color all aquatic plants. With low amounts of phosphorous and no copper, the pond spikes have no adverse effect on water quality and are non-toxic to fish and plant life.