I just opened my pool and I know it's way to late in the season but we have had nothing but rain for months. Anyhow my pool looks like lime kool aid and I put 2lbs of shock in and a quart of algecide (per pool place) and my pool developed a brownish foamy scum on top. I took them a water sample and they informed me that I am in chlorine demand and required 70 lbs of shock to fix the problem. I pumped my water out below the skimmer and then began to refill while still pumping out old. Should I continue to use the shock bags or switch to bleach