Ehm...That's like one of the most wrong sentences I've ever read. Pumping air into the res is whàt keeps it fresh. Have you ever grown a hydro plant? You do realise most of us grow in nothing but water with shit loads of air pumped into it.
No, keeping it circulating and keeping the temperatures down is what keep it fresh and at a higher dissolved oxygen level. Pumping air in through an air pump is taking the air from your room, pumpingbin whatever microbes could be floating in that room and adding them to the water creating a temporarily oxygenated reservoir that dissipates quickly thus creating an extremely helpful environment to grow mold, fungi and bacteria. If you want proper dissolved oxygen, you lower your reservoir temperatures. The lower the temp of the water the more dissolved oxygen is permanently in the water. Also by using an air pump you're taking the air from the room environment and pumping it into the reservoir, which as we stated before pumps any and all microbial entities into the reservoir and it also increases your temps since you're taking air at the temperature the compressor is in and passing it through the compressor, further increasing the temperature.
And to answer your question, yes, I've been successfully operating Undercurrent and RDWC systems for well over 10 years while helping well known companies develop their systems to make them not only more efficient, but easier to use for the end user. Always pump oxygen into each individual bucket where there is a plant with roots. NEVER use an air compressor to pump air into a reservoir. Hook it to a chiller, this keeping the water consistently moving, maintaining a consistent temperature and allowing for more dissolved oxygen by keeping your temps low. If you don't believe me about colder water holding more oxygen, go fill a gallon jug with water all the way to the brim, out a cap on it and place it in the freezer until it freezes solid. The reason thenjug explodes/splits is due to the excess dissolved oxygen/air levels on the water as the water cools. But please, continue telling me I have no clue what I'm doing.
If there's no roots in the container you DO NOT pump air into it