1. If you vacuumed to waste, then the cloudiness was probably algae stirred up by the process, rather than algae blown through the filter

2. If your CYA > 70 ppm, you DEFINITELY need to stop the dichlor. In my area, at least, Walmart has restocked pool grade (10%) bleach. You could use cal hypo, but if your calcium + alkalinity levels are high, doing so might cloud your water.

3. The fact that your backwash water was dirty from algae is a fair indication that you DO have enough sand.

4. Aerating only raises pH IF the alkalinity is substantial.

Good luck.