Geoffrey, that is one heck a lot of critters in a small tank! You are better off doing 2x a week 50% water changes if you are having issues so as to whip the tank back into shape before reverting back to perharps once a week 50-70% water change. How sure are you of your CO2 levels? I know you are doing 24/7 with the CO2 and I have done it personally. The CO2 levels tend to be chronically low down to 10ppm at the end of the cycle so as to avoid an overdose during the night. Not a good method in my opinion and that is properly why the BBA broke out. Do a good review of your CO2 by checking the pH both in the am and pm times before lights on and off for the entire week. If things seems fine and within range, add a touch more CO2 incremently till you get the plant growth you know you should have but monitor for abnormal critter behaviour. The BBA should stop growing if your CO2 is indeed high and good. (I have seen it with my personal experience..) The BGA seems from bottoming out of NO3. The 18ppm of NO3 that you are dosing per week was enough but properly bottom out when you decide to stretch it to two weeks. You can add more like 2x the amount you are currently doing but the issue with not doing large water changes will make potential buildup of nutrients more serious if you overdose.
Regards
Peter Gwee
Bookmarks