Great site! Love the enthusiasm! You are all striving for a good cause.
I was very impressed with the idea of using an air pump to lift the water. All my hydro attempts so far have used a miniature water pump, which tends to heat the water too much in summer, and, more significantly, produces a water flow that may be too fast for the roots. The air pump should produce a more suitable flow rate and should also consume less electricity.
What I am not happy about are the metal fittings. I read a book on hydroponics, and it was dead set against there being any metal parts touching the water. Metal, in contact with well oxygenated, continuously flowing, water, is a blatant invitation to corrosion. If you’re operating at the recommended pH range from 5.8 to 6.5, which is acidic, then probably, even stainless steel doesn’t stand a chance. I myself had a galvanised iron handle on the plastic bucket I was using earlier. This handle was barely touching the water, but soon the area around it developed a gritty feel.
My suggestion is to have all the metal parts replaced with plastic/rubber or ceramics/glass.
Keep up the good work.