I have the same out of the box system for my 20g long, lots of plants and had bba and all sorts of algae, the little bottle cleared it in a month, works fine for me. It takes 2-4 days for bubbles to start and then if you do not close the cap tight enough, stir the sugar and use too warm of water, then it could mess things up.
But I am looking to get 2l soda bottles and set up several together for larger tanks. Q if anyone knows, one 2l bottle is good for how many gallons?
♡ Forever Farms Babydoll Southdown Sheep ♡