No one is saying the product doesn't work but as I posted in your thread algae killing chemical products are not recommended for use in tanks. If you balance your tank by keeping nutrients at proper levels, run lighting for an appropriate time, etc., you don't have algae issues and you don't need to use dangerous products. The algae will come back if the issues within the tank causing the algae in the first place aren't addressed. So what, then you keep using the chemicals over and over when all you need to do is correct the problem in the tank in the first place. I've been keeping tanks since the 70's so I'm pretty well versed in this.
OP, how long do you run your lights? When you have an algae issue running your lights 6 hours max is recommended. The other option many people swear by is running your lights with a siesta period. Meaning run them 3-4 hours, lights off for 2 minimum, then lights back on for another 3-4 hours.
Do you know your nitrate and possibly phosphate levels? Then as Mumma said if it's a new tank the brown algae is diatoms which will run their course and go away as soon as they use up the excess silicates in the water. Can you post a picture so we can identify the type of algae you have?