Two comments re preceding post. First, I would recommend using two float switches wired together in parallel (one lead on each switch joined to one lead on the other switch and hooked up to a common terminal, other leads on each switch getting their own separate terminal connection), one high and one low. Low switch is used as primary and should turn pump on when water level drops and float drops with it. High switch is a kill switch and should be set so that when the float is down, it lets the first switch do its thing but when the float is up, it prevents refill pump from turning on or kills it. (Note that the code for switch 2 has to be after the code for switch 1 to ensure that it has "the last say" in the matter.) Here is my code for this:
If Switch1 OPEN Then RFL OFF
If Switch1 CLOSED Then RFL ON
If Switch2 CLOSED Then RFL OFF
Switch 1 has its float oriented so that the reed switch inside is open while the float is high (don't want it getting corroded and sticking shut); it closes when the water level drops to turn on the refill pump. Switch 2, on the other hand, has its float oriented so that the reed switch inside is open while the float is low; it closes if the water level rises so much (e.g., if the first switch sticks closed for some reason) as to potentially overflow the sump to prevent that from occurring.
You can get all the components you need -- switch, heat-deformable hanging bracket material strips, tubing to fit over the leads coming out of the switch (put silicone around the base of it and in the top of it to prevent water from getting into the leads), etc. -- at aquahub.com
Second, unless you want to spend a lot of time bent over tiny pins and/or are very good with a soldering iron, I'd recommend using the breakout box. Here is a link to thread re my experience doing it DIY. :
http://reefcentral.com/forums/showthread.php?s=&threadid=1135897&highlight=solder