I also meant to say that I don't think anyone else has said this, if so, i apologize, i read this entire thread so maybe i just forgot, but anyways... I have been using eight air stones to brew my tea, hooked up to a 15l air pump, so that two air stones run from one outlet. This produces a weak stream of bubbles from each one. My pumps output is adjustable, and i turn it up slowly until i can see a good bit of bubbles coming from each one. I use 4 inch air stones, so even at full blast, i could easily get more air with one stone and a bigger pump. But this is what I want, just so all the air stones have some air passing through them. As the tea brews, the bennies take up residence in them, and I switch out the air stones when i do my res changes. If you can afford to buy an extra set of air stones do so! I think this really helps the bennies get established in your res after a nute change and scrubbing, and rinsing. I run 10 gallons of bleach water in my rdwc after it has been cleaned and then rinse with ro again.Then drain and dry the system. It's tedious and probably not needed, but i learned my lesson the first time about lettin things go too long. Then i use the tea and my bennie condo's and my roots are amazing now, I use 8 air stones in each system, so the ones that come out get soaked in bleach water, ran in bleach water, then boiled and dried. And they eventually make it back to the tea and a res, I have a lot of extra air stones, and the boiling helps clean them out a bit, they work like new afterwards. Sorry such a long post, but i'm stoned and it happens. Peace!