Pumps approximately 1 ML per pump Replaces dosing the cap on our fertilizers 1 Pump Treats 10 gallons of water The pump head is an alternative to our dosing caps. It can speed up the dosing process for tanks up to 50 gallons. Store fertilizers with pump heads upright to prevent any leaking. Wipe nozzle clean or dip into aquarium after dosing to help prevent fertilizer crystallization of the nozzle tip. Each pump head comes in it's own cardboard box to protect it during shipping.  Fits: 28/410 neck twist