okay i think i won the battle, turn out it rhizoclonium. I took some of the brown algae out of the tank and let it dry up. When it dry up it turn green so i assume it rhizoclonium. So i did a 50% water change and add 3ml of excel per gallon. The next day it turn green and most it melted away. I did another major water change 2 days later and dose another 3 ml of excel per gallon. The fish is okay including the chilli rosboras, otto catfish and fire red shrimp. I wouldn't overdose excel because of the shrimp but i been adding 1ml of excel to 5.5 every day so most of the fish/invertebrate was expose to excel before the overdose to allow them adjust to the excel.