I am use Bleach to do the first cleaning/sterilizing. I put it in a spray bottle extra strong (like a 50:50 mix) and that is usually done twice. I let it sit a moment before scrubbing the system down where ever I can and then rinsing.
The final part of my cleaning is rubbing alcohol in a spray bottle. I make sure I spray it EVERYWHERE i can possible reach. Then just let it dry on it's own.
It is probably over kill, but it definitly works.
While running the system I use 1ML per 4 gallons (makes it about 3ppm bleach) which is about the standard for pool sanitation. I also have a UV filter in my res ($50 at petco) and I have that running 24/7. My res is still perfectly clear and I havent done a full change in over a month. I just pull out a gallon every week to water the potted plants and replace it with a fresh gallon of solution. If you use bleach you have to remember that it will work as a PH up. It has a PH of 8+, so I put in the bleach before checking the PH and I set it at 6.8 and let it settle down as the bleach evaoporates to probably 5ish and then bring it back up. The plants are doing well and showing no signs of deficiency as they go through the whole PH
nutrient range over the course of a day or two as the bleach disipates. This is more of a way to be lazy as I am experimenting with hydroponics than a final intended method. It also might not be a great way to manage larger plants. I am only growing some leaf lettuce in my system. I also am not getting TOO far into hydroponics while inside because it is going to cost extra in equipment to get the humidity in the root zone up being in the air conditioning. I am thinking a fogger (I am trying to find one of those sonic humidifiers to pull the parts out of).