A pair of lawn irrigation valves and a tee fitting make draining reservoir tanks easy. Green lines depict sections of common garden hose. Irrigation valves used are all plastic and thus impervious to corrosive nutrient solutions.

For normal operation, close valve #2, open valve #1.

To drain tank, close valve #1, open valve #2 and turn on the pump.

Be sure to return the valves to the operating position after draining- unless you want your new tank of sauce to go down the gurgler!

Several copies of the above can share a single drain line, as shown:



I just use a normal garden hose to fill the tanks at the moment, but if all the drain line connections had hose clamps, it would be possible to refill the system via the drain system.