I woke up to a near disaster this morning, with about 2/3 of the water in my fish pond gone. I've tightened the filter and added a small amount of water back to the pond. The fish (goldfish and 1 koi) seem active and ok so far. How much water can I safely add back at one time? What else do I need to do to get the conditions right for the fish and plants? For the past year I've just cleaned the filter and sprayed in water once a week or so to replace whatever has evaporated. The fish came with the house, so I really don't have a clue. Any advice would be greatly appreciated!