Durable, flexible, and easy-to-plumb polyethylene tubing ideal for aquarium reverse osmosis applications. AquaticLife 1/4" Polyethylene Tubing, Blue is nontoxic and highly resistive to stress cracking from liquid. Use blue, color-coded tubing to indicate filtered product water. Plumb from last stage reverse osmosis or deionization canister to a storage reservoir or aquarium. 1/4" x 50 ft.