Try a 500 GPH bilge pump and bilge tube available from any marine store or catolog like bass pro shops. Sit the pump in the bottom of the tank and you have in effect a garden hose. Can hook up to a 12 V battery and get a cheap charger or you can get a little box thing that you plug in to 120 AC with 12 V DC output. (elctronic supplyer)

Also to speed up watering in soil grows add a layer of pea gravel, sand and DE mixed together to the top 1-1.5" of the container surface. You can then pour the water real fast without having it disturb the surface and dig a hole. When your watering several plants at once, it can save a lot of time. The addition of the DE will kill the soil insects.