Make sure it is cycled by adding some ammonia and then testing to see what happens. You may need to allow too few bacteria left in the new set-up to multiply. However, you cannot add ammonia to a tank with fish or inverts as it will kill them at worst and do serious harm at best.
You should hveE moved the old media to the new filter. You should have saved the top 1/2 inch (or all) of the substrate and kept it wet to be used in the new tank if possible.
What is keeping the water free of ammonia where the fish now are?
The green is an algae bloom from excess nutrients in the water.
Unfortunately, the best time to have asked questions was before you did things. But what is done is done. Now, you need to provide a lot more information for us to give the best advice here. What was in the tank right before you did any of the above. Where is the old filter and its media? Was there substrate in the tank? If so where is it? How many live plants were in the tank before the redo began? How many fish are there now and what sizes/species? Also what are the your tap and tank water params- pH, KH and GH?
All of this stuff matters in terms of the cycle and keeping the fish safe.