Rinse cubes very well but gently with water produced by reverse osmosis and deionization to remove any dust or fines. Place cubes in a plastic container with enough aged aquarium water to cover and allow to condition overnight. Place in an external filter system (do not fluidize), with slow to moderate flow. If a filter with flow control is available, that will be a plus. Always provide fine mechanical filtration ( i.e. filter floss ) ahead of the cubes to prevent fouling and behind them as well ( sandwiching them in filter floss is recommended ). XPort PO4 Cubes are powerful and can remove phosphate too fast, so that corals may close up in reaction. If that happens, simply remove half of the cubes and reduce phosphates more slowly. Initially use about 1 XPort PO4 Cube for every 20 U.S. gallons ( 76 L ) of system capacity. Measure the phosphate level. If it is high, then add 1 more cube per day until you reach your goals. As cubes exhaust, it will be necessary to replace them with newly conditioned cubes. Discard old used up cubes. Most systems will require a total of 1 to 3 XPort PO4 CubesTM total per 10 gallons ( 38 L ) of capacity.
A flow-through rate of 1 - 3x the total aquarium volume per hour is recommended. Do not fluidize; fluidization serves to decrease filtration efficiency and may cause gradual deterioration of the material, potentially resulting in dispersal of harmless, but unattractive, dust throughout the system.
Caution: Keep out of reach of children (contains iron). Not for human use or consumption.