Thanks for all the provided info four20; despite the few small setbacks/minor issues you've had it looks like you have a nice little garden going there, I hope you get the desired potency your looking for.
Like I said before, I am taking great interest in your endeavors because you are almost to a 'T' following my plan of attack. I have a water farm, and am about to purchase a DR120, especially after reading your opinion of it.
I do not have as much indoor growing experience as you do my friend, but I have grow outdoors a few times and have read extensively about DWC, drip systems, and ebb and flow hydroponics. There is no great way to gain experience besides actually doing it like you are, but, considering you haven't already figured this out, I think your running into one of the problems that I imagined I would once I had things to the point you do. As you know, all plants even different strains of the same plant all have there own particular wants and needs, some plants, from what I've read, can stand much higher/lower PH's and PPM readings than others. Since you are growing 4 strains all out of the same community res, you are not able to cater to each individual plants particular preferences. ie. whatever your doing now the SC appears to like just fine, while on the other hand, the SD does not.
What kinda PPM readings do you have? To be honest I have not even heard of some of the nutes that you are using, though I'm sure they could be just as effective if used as the plants desire. I plan on using a suit of 6 Fox Farm nutes (3 for veg and beginning flow, and 3 more for finishing flower) and also giving the General Hydroponics FloraGrow, FloraMicro and FloraBloom a try perhaps before I get fully invested in the FoxFarm nutes, was the Flora series not proforming as you had hoped, or did you just find something better?
Sometime in the future I may graduate to this TDS (PPM) meter:
High Tech Garden Supply
This will read PH, EC, and PPM, as well as temps, I like it
I will even be facing similar temp issues as you, a little to cold in the winter and way to hot in the summer. This, I fear, will be the hardest and most expensive hurdle to try and over come. Any detailed insight into how your handling that is more than welcome. eg. What heater are you using? and are fans alone enough to keep temps down where they need to be? FL out.
Happy growing, God bless!