Advice on a deposit

[Shari DuBois]

My husband and I purchased a rental property already rented out. The house was dirty inside but the yard was in good shape. The renter asked if she could put up a pool and my husband said it shouldn’t be a problem. However, it was a large pool that killed all of the grass. She has moved out now and we decided to not deduct any money from her deposit for the cleaning because we don’t know the condition it was in when she first moved in, although she did sign our cleaning agreement. However, we deducted $300 for the grass re-planting (which would have cost a lot more had we hired it out). My husband told her that she is still responsible for returning the property to the condition it was in when we bought it. The former tenant thinks this is unfair and is threatening small claims court. Any advice from those more experienced?