I haven't read all the responses in this thread. I did this years ago. Here is the old post in case it provides any additional info.
I wired an Intermatic brand, standard in-wall, spring wound, house timer in an electrical box. I used a good quality extension cord, cut one wire (hot leg) and ran it to the terminals on the timer, and then plugged my main pump into the end.
When I feed, I turn the dial on the timer to whatever time I want. The pump stops, and all my food stays in the main tank. After whatever time I set it to, it turns back on.
The beauty of it is I can never forget to turn it back on. The timer I bought also has a position that will keep it off indefinitely (called Hold), if I want to use it.
Make sure the timer you get has N.O. and N.C. contacts. Most timers turn things ON for a period of time. They use Normally Open (N.O. ) contacts. You want it to turn the pump OFF for a period of time. You want one that also has Normally Closed (N.C.) contacts.
“Normallyâ€Âmeans its normal, or rest, position (when the timer is not doing anything).
Normally Open means: In the “rest†position, the circuit is open (disconnected). No power goes through the timer.
Normally Closed means: In the “rest†position, the circuit is closed. The contacts are connected. Power is going through the timer to whatever is wired to it.
You want to run the wires to the N.C. terminals. I got mine from my local electrical supply store.
I used the Intermatic, model FF32HH (SPDT) timer. It has the HOLD feature. I chose a 2 hour timer because a simple 1/4 turn (one twist of the wrist) will turn it off for 30 minutes (rather than having to turn the knob twice). Wire it according to the “Reverse Action Switching†Directions.
The “FF†model has a brushed aluminum faceplate.
You can get an “FD†model. It has an ivory color faceplate and knob.
You can also get them with different maximum times (1 hour, 2 hour, 4 hour).
Hope this helps.