I use 6 way hth test strip n also take the water sample to the pool store they tend to match most of the time. Can I use 'Pool Brand' Algecide 40 to control this problem? It seems to create foam in the spa water! On using simple liquid bleach (sodium hypochlorite, 6%) can I directly add it to the skimmer? It has been raining for last two days n the afternoon test was cya 100, fc 0, th 100,ph 7.2 ta 80.