Question: "Should I use that drain cleaner stuff if I have a septic system?"

Answer: No, One reason... the most common, over the counter drain cleaners you by at the grocery or home improvement stores are mostly composed of bleach. Bleach kills bacteria, and bacteria is a septic systems best friend. Bacteria is what disposes and basically eats all the waste in your septic system. The best thing to do for a clogged drain is to call your local plumber (ME!, 972-318-3800) and get him/her to use a drain auger to clear the blockage... Thanks for your question Lisa/ Lewisville