I am a newbie to pools. I have read up on the BBB method and am excited to use it. I was talking with my hubby yesterday about all that I have learned and he was concerned about the impurities in cheaper bleaches. He said he had heard of lots of iron in cheaper bleaches. Is this something I should worry about? Right now, I am purchasing Aldi's bleach, which says it is 6% sodium hypochlorite. Thanks.