If your ph is below 6.8, that is a very big concern. Get some Borax and add a half a box slowly to the skimmer while the pump is running. Then let it circulate for 3 or 4 hours, then retest ph, and add more Borax until you get it to 7.4-7.6. Also, add 6 quarts (1.5 gallons) of plain, unscented bleach to the skimmer - again while the pump is running. It is OK to add the bleach right after you add the Borax.

That is just a start. We really need more testing results to really be able to help with your problem. Get a better test kit. At the very least, the 5-way test kit from Walmart. We need more than just ph and cl readings to be able to help you much.