The most important thing to remember when considering your pump...is the fact that around 70-80% of the volume of your system will be used up by the grow medium!

For instance...my grow try takes 7-8 minutes to fill [ WITHOUT anything inside it].When the tray is FULL of clay balls..it takes just under 2 minutes to fill!

I'm using a 6 watt pump for about 30 litres of grow tray.

A smalll pump will easily feed a small grow.

Think about the total volume of your system then subtract 70% of it's volume then rethink!

My pump cost me only 10£
Easy Roller Reviewed by Easy Roller on . Hydro Pump Question I am building my first hydro system, small 5 grow bulbs. My question is how big of a pump do I need in order to fill 5 1/2 sized 2liter bottles from my res? On this type of design does the pump need to stay on or have watering times? My medium will be shag moss or clay. Below is a pic of the design but I downgraded to a 5 slotter. DFG Rating: 5