Green for water, free ammonia, should not be in your tank. Even if you kill it all is said and UV disinfection is now rotting, it will only repeat the cycle back to ammonia, ammonia is what causes. You must remove the source of the problem, the problem itself. You might be surprised at how much you can remove the dirt green water tanks. Presented at the Fifth dark brown bucket of water, you start to get some idea of ​​just why it can become green.