My 75 gallon oscar tank was infested with bba a few months ago when I decided to try a couple plants in his tank. Now the plants are gone and I can't get rid of the algae. I read that overdosing Flourish Excel can get rid of it, but how much can I dose without hurting my large oscar? The initial dose I used last night was for 90 gallons. Now it says add 1 cap a day. How much more than that should I use?