General Hydroponics recommends ppms of 800 to 1000 in the instructions that come with their aeroflo systems. Aeroponics and dwc "bubblers" are totally different than straight hydro. I have mixed GH nutes according to the directions, I think if you exceed the (strong) directions on the bottle, you'll get over 2000 ppms especially if you use any additives; this makes my meter blink on and off, things get weird...And plants suffer (usually). If you try excessively strong nutes, and rely on "cutting back" when things go wrong, then unfortunately the damage is already done. It's much better to underfertilize than to burn your plants. If your plants are healthy, and your nutes are a little weak, then the plants will just use more (the res will drop more quickly). #1 mishsap for newbies = overfertilizing.