I am just learning about BBB...I am starting to understand the long term effects, but have a question about cya staying high. I live in a High Rain area, therefore, ph is lowered on a regular basis and backwashing water replacement common. I have always been told not to let the cya zero out. Now that I am researching BBB, is there a cya recommended level? We have rain every day this time of year, sometimes twice a day.