xlr8 Thank you for your insight it is very much appreciated in fact I am going to try your suggestion on DM "zone" out on next water change. fyi.. nutes I run are as follows.... GH micro grow bloom and during flower I add liquid kool blooms . I fill my res to 55 gallons and mix for 45. so that leaves quite a big buffer. My ph is stable I use GH up or down as needed but mostly down.
I'll second X's recommendation of DM Zone. He's right on the money with everything about flood & drain vs (R)DWC. I'm guilty of applying some of their lessons to my system though. I have 2 air pumps into 4 stones in my res. When it comes to DO, we have one of those "can't hurt, might help" situations. I agree, it's probably not helping the root zone get more O, but it makes me feel better about keeping the res free of anaerobic pathogens.
The whole reason I can't bring myself to do DWC is because of how much O a flood and drain system provides. In every hydro system that leaves roots submerged, it's a constant fight to keep the roots from drowning. Flood & Drain just seems like the obvious solution. I also feel like oxygenating the roots is even more important than the water and nutrients. I've seen plants with roots that were too wet or too dry, but never too oxygenated.
That being said, once I get my basement dialed in a bit more, I am going to build a 5g DWC to try.
I use almost the exact same recipe, except I also use GH FloraBlend. The 2 parts of GH's simple recipe I don't use are the FlorilisciousPlus and the Dry KoolBloom. I start with RO, and find the GH stuff to keep my ph real stable as well. The other things I add are calmag, Hygrozyme, a little epsom salts, and some Superthrive. I'd be surprised if you didn't need some calmag, but you know your plants better than I do. I just know that even when I used GH Flora in the 90's I had to add epsom salts (I wish I could remember what we used for Ca). I'm running the Hygrozyme because I know I have decaying matter in the system, and it's supposed to help 'clean it up'. The Superthrive is just because I always used it back in the day, and it's relatively cheap as far as additives go. I think it's real important during stressful events like transplanting, but I could probably forgo it in flower.
I also do the same thing as you with regards to mixing my 50g using a 40g recipe. I found that my plants were starting to burn around 1500 ppm, so I shoot for 1300ish now. I'm currently running several strains though. I know some of these could take more though. You'll just have to get to know your strain and figure out what she likes.
Oh, with the "Zone", I'd add in at the 55 gallon level, as this isn't so much "food" as "disinfectant" and you want to make sure you are covered. I use 2 ml per gallon typically.
I do this too. I mix a 40g nute recipe into 50g, but I add the Zone for all 50g.
I hate washing hydroton, but I hate wasting it more...
Sometimes I swear you read my mind! That's exactly my feelings, but then again, I hate to waste anything.