Indoor swimming pool BAQUACIL problems, please advise

HI, I currently use baquacil and baquacil products in an indoor swimming pool. For years now we have had browm algae problems, and the stain on the gunite pool bottom is growing larger by the day. I have not found a solution to kill the algae growth. I'm considering switching to chlorine/bromine. Baquacil was chosen because it is odorless. Has anyone had such a problem, and what are some suggestions? Additionally, i have been told that a gunite indoor, inground pool should not be drained because it will cave in due to lack of water pressure. Please advise. thanks, Judah
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