Sounds like cyano, a bacterial gunge. This can be triggered by an inbalance of nutrients etc in the tank (as a result of the move) or be introduced with a plant.
How many plants in there? Lots of plants will use up the nutrients and starve the cyano. Also, cover the tank in a blanket for 3 or 4 days as this may kill it off.
As a last resort, erythromycin will kill it. This is a prescription only medicine so you need a friendly chemist or Dr to give you a tablet or 2.
These pills are usually 400mg each. It as been suggested 400mg/100L. Someone else said 250mg/100L. I seem to remember using 4 pills in my 280L tank which was probably overkill but I didn’t know the dosage at that point and it certainly worked without harming the filters or fish.
People worry about it killing the bacteria in the filters but I kept my filters running the whole time and noticed no difference. I was told the bacteria in the filters is the wrong sort and is unaffected by the erythromycin. Something to do with gram -ve and gram +ve bacteria.