saw this thread and thought i'd throw my 2 cents in. i've been in coco for over ten years now, and will never go back to dirt, lol. i always use a good 10-15% perlite. good for air to roots. i feed full strength (usually around 800-1000 ppm.) every day once they're established in veg. always allow a good 15-20% run-off. run-off is key. if you feel you're having build-up issues, increase run-off amounts. i've read in g. low's "integral hydroponics, and asked him about it," that coco prefers several small feedings per day, rather than one or two big ones. i'm almost ready to put together an auto feed drip rez system. i never flush, until the end. although some feel it's not necessary. i use house and garden coco specific nutes, and some of their supps. real happy with the h&g line. and as someone said, their roots excelurator is great stuff, it is "very," pricey! i use fulvic and humic acids. i use pro-tekt for ph up, and a 9% phosphoric acid solution for ph down. i like the bagged coco, the bricks are too much work, lol. i do flush it with r/o water, and don't bother with ph'ing that water. i use r/o water to feed, and never use just plain water. it seems that coco doesn't require the high ppm's that soil growers use, but i see some use this method. i never check my run-off ph, unless there's an issue, and in all these years, there hasn't been any. i feel that chasing ph is a mistake. i mean, who cares what the run-off ph is, if your plants aren't displaying any issues? i re-use my coco 3 times. i use hygrozyme to help clean it up. i'm a bit high, so if this makes no sense, sorry, lol.... leaving tap water out to get rid of chlorine may not be helpful in all areas. some cities are using chloramine now, and that won't work.. never had to use cal-mag either. i wonder why some need to??