pvc overflows and newb questions...

[YMCFLAMESROCK]

Hi everyone... new to the forums and reefing and need some help.
just want to know if there is an expert on pvc overflows in calgary that could take a look at my setup. (over the glass pvc overflow).

Started a 54 g tank and decided to add a sump after the tank was running.
built couple of 3/4 pvc overflows and they seem to work when ever they want.very intermittent.
had couple of mini floods, no real damage done. but it is starting to frustrate the crap out of me.
need some help in figuring out why they keep loosing suction.
Also general question on how long it takes for dry rock to start changing color?