I stumbled across this while looking for various, readily available planters for hydroponics and immediately saw applications for potted plants and pets as well.
The Power Ade bottle has a valve in the cap which forms a water tight, low pressure seal around the tubing. This allows for very quick change applications with no additional modifications. Appears very durable under reasonable conditions..
I hung it upside down, indoors and out of the sun, and although it looked like nothing was going on, it emptied itself, in and around the 24 to 36 hr range. This time could easily be varied through various means.
Step 1: WHAT YOU NEED
1 ea Power Ade bottle with cap
1 ea length of 3/8 inch OD Vinyl tubing as req'd
Step 2: WHAT YOU DO
1. Cut desired length of tubing at the desired angle and shape of the tip.
2. Insert tubing into hole in cap and through valve.
3. Pull back slightly on the tubing to "seat" the valve.
4. Fill bottle with liquid of choice, screw cap on tightly and turn upside down. Watch out for initial spill as pressures equalize.
5. Find an application for a drip feeder or use it as a hydroponic planter, either drip or "flood and drain".
You may want to do step 5 first, or at least before step 4.
Note: Flow rates can be adjusted by adjusting the tube length, the angle of the cut, the shape of the tip, the diameter of the opening, or whether it is touching something or feeding a "wick". Aside from, or in conjunction with the previous mentioned methods, an adjustable air leak can be introduced into the bottle to add a different "level" of flow rate control and would probably be useful in conjunction with a wick system.