Thats good, thats what you want. It is the dust and debris from the crushing process. When the water clears up, mix up the substrate with your hand and keep using the hose to flush the stuff out. When the water is coming out clear after a few mixings it should be done.
Before using it make sure you use a good declorinator to make sure there is no harmful chemicals from the water from the hose.
I left the substrate in the bucket with water an inch above and used a bubbler to help circulate the declorinator for 24 hours. To speed up the process use RO or DI water in the bucket instead of tap water.