cycle timer
could it be modifyed to run 120 on 120 off?
Sure, just remove the diode. Btw, it looks like the 1sec/120sec diagrams & titles should be swapped, the output (pin 3) is high while the capacitor is charging, and low while the capacitor is discharging. The component values shown won't give you exactly the same ON/OFF periods, but it's pretty close. With this circuit, the ON time is always longer than the OFF time since the cap charges up through R1 & R2, and discharges only through R2. You can get close to a 50% duty cycle by making R1 small relative to R2, which this circuit does.
For the 555, the CMOS version allows you to use higher values for the timing components, and can achieve longer timing periods, up to around an hour. The standard bipolar version (LM555) you'll find at Radio Shack is actually a better choice for your 2 min. timer (ignore my earlier comments), as it can sink or source more output current than the CMOS types (up to ~200 mA vs. 50 mA), and may be able to drive your pump directly.
You can measure the pumps' current draw by setting your meter to read current (milliAmps - mA) and inserting the leads in series with the pump. If the draw is over 200 mA, you may need to add an external drive transistor to the 555's output. Try it first using just pin 3. You can either sink (pin 3 replaces pumps' ground lead) or source (pin 3 replaces pumps' positive lead) current to the pump (since it's waterproof & isolated), the 555's pretty flexible. I assume you're running the timer off a 12V supply. The 555s' output can drop up to 2.5V at its maximum output ratings, so if your pump seems to be running slower, again you may need to add on an external drive transistor.
A few more things. In the circuits shown, connect pin 4 (reset) to pin 8. You should also probably bypass pin 5 (fm) to ground with a 0.1 uF cap, and add another 0.1 uF power supply decoupling cap across pins 1 and 8. Also, place a reverse-biased diode like a 1N4001 across the pump coil to protect the 555 from the coils' inductive spike. For testing the circuit to see whether it's wired and operating correctly, you may want to temporarily replace the 784 Kohm resistor with something like a 10 Kohm resistor (or just put a 10k in parallel with the 784K). This gives you ~2.5 sec on/1.5 sec off times, and beats waiting two minutes every time you tweak something. A 330 ohm resistor in series with a LED to ground driven from pin 3 is a useful visual indicator. Don't be afraid to vary the component values if you can't find the listed ones, just follow the given formula. Good luck!
i can read a blueprint and build $300,000 homes...
And I can design little blinking circuits... You probably have the more valuable skill set.