Initial nitrogen cycle

For the system to work properly it is necessary to establish the bacterial film which will convert the fish waste into something which the plants can utilise.
This film will grow primarily on the surface of the gravel in the growbeds and would have happened naturally without intervention from me. However I wanted this to happen as soon as possible so I took a big sponge filter out of a filter in another fish pond I have and rinsed it out in the water in the big 4000 litre tank. I then got some dead fish we had in the freezer ( flathead fillets and squid which had been forgotten) and suspended this in a couple of nylon bags in the fish tank water for about 3 weeks. I also bought a comprehensive test kit so that I could monitor the progress of the establishment of the cycle.
Unfortunately I clearly missed the peaking of the ammonia production and so don't know how long that took to happen. By the time I got around to testing for all Ammonia , Nitrite and Nitrate the levels of the first two were basically trace to nil. Nitrate was quite high and has remained so ever since. This is not bad as the system had clearly cycled and all ammonia is being converted to nitrate before it has a chance to hurt the fish.