It takes about a month for the culture to settle and infusoria being available in numbers. If you let the water settle for 5 minutes then you should see some small white specks moving around the water. These are the infusoria. The water will also smell nice when the culture is ready. Before this the water will stink especially if it isn't aerated.
For best results you should have an airline or airstone bubbling away in a corner. This will increase the oxygen in the culture and help mix the water thus providing a cleaner and faster growing culture. When you need to harvest the infusoria you remove the airline and wait 5-10mintues for everything to settle, then use a bucket to scoop some of them out.
Once the culture is running properly you should add a couple of crushed lettuce leaves to it each day, and top it up with some clean fresh water.
