Well, after many dollars and many late nights of frustration because of the fact that my parents would turn off the filter due to this crackling sound i think i found the problem.
First a little background.
I got the filter used and the previous owner had sand as the substrate and it came from an area that had really hard water... i mean there is still hard water deposits outside where i cleaned the tank and accessories... But anyways the impeller made all kinds of noise so i went out and bought a new pump and impeller.
Now it still, occasionally makes this really bad sounding grinding sound. Like the impeller is going to break.
Now before you all say "clean it"!... it is brand new and not had enough time to get crap in it.
Anyways, my brother told me that it happens every morning when my mom uses the hair dryer... news to me... so i thought... thats too much of a coincidence for it to happen every morning...
I had it plugged into a power strip so i thought maybe there was a fluctuation in power and thats what was causing the impeller to make the noise.
So I have a variable AC power supply and a digital multimeter and I hooked it all up and was able to make the noise start and stop at will!!!
This is great because now i know that if there is a drop from the 112v that my house is running on fluctuates even .1 volt below 111.0v it will make the noise.
So now i am in the market for an UPS (uninterpretable power supply) to limit the fluctuations.
either that or put my electrical engineering schooling to work and design a
circuit that will smooth out the fluctuations.
Now i am sure that i lost a lot of people on this, but i was just happy to actually solve this problem... well not really solve, but determine the source of the problem.
