Purchase this item and get 
Prevents diatoms by removing silicate.
Key Features:
• Filter material for the removal of silicic acid (silicate) in fresh and marine water to prevent diatoms.
• Rinse, fill in filter bag (enclosed) and place in filter. Rinse after one to two weeks.
• Diatoms can form brown unsightly deposits on gravel, decoration material and plants.
• Silicate content can be checked with silicate test. Result: values below 0.4 mg/L silicate prevent diatoms.
