Stress zyme doesn't do anything its just another thing to ripp people off. Maybe the reason the water is dark and cloudy is because stress coat isn't a dechlornator, well it is but it's main use is to help calm down stressed fish and help reproduce there slime coat if they jumped out of the water so if I was you I would go to your petstore and get some decholrnator called amquel+ I use it and it is fine. You should use 1 teaspoon for the 10g. Also you will need to empty the water out in the 10g, rinse it out including the gravel and fake plants, refill it and treat the water with amquel+ or any other decholrnator you see but make sure to read instrustions on how much to add per 10g of water.