I'm new to hydroponics and I have set up just one beefsteak tomato vine as a test. It is growing exceptionally well, it's about 150 cm high, still growing and is covered in flowers and fruit. I have a 30 litre reservoir with a tiny aquarium pump feeding a constant stream onto the top of the roots (maybe 100 l/hr?). The grow tub over-flows back into the reservoir and holds about eight litres of nutrient, 250mm deep, just below the pot of clay balls. The root growth is substantial and looks healthy - white to gold in colour. I have just today installed an air pump with two small air stones. I have done no pH or EC testing although I have ordered some gear to do this.
As insurance, I have been dumping the nutrient every two weeks or so. Should I also rinse the roots - say with a spray nozzle? Clean the tubs?
My key question is - with the new aerator, do I still need to replace the nutrient? If so, should I do so with the same frequency? Next year, I propose to set up four plants in a system that will hold 100 litres of nutrient. That will cost about AUS$8 every time I drain the system - I'd prefer to avoid that if possible.