Alright bru. This is the kinda thing I think everyone does differently depending on taste. First off, the reason the chart has the escalating numbers is that DM thinks the plant is going to want that much to be happy. Those numbers are pretty damn high. For example my grow with the CJ and SG... my ppms never ever got above 1200. And that was after they climbed. I filled the tanks to mearure around 1000-1080. The DM calandar goes up to 1750. That's too high most of the time. Not always. So that's that.
The great thing about DWC and I think this will be the case in your setup as well, is that you can tell how hungry the plants are by watching the ppms. So if you fill the tank fresh to measure 1000 ppm. And you check the next day and it reads 1100. That means the plants drank more water than they took nutrients, so the ppms climbed. If you fill the tank and the next day it is 900, it's the opposite, so the plants want more nutrients than water. So you can adjust using that little rule.
Ok when it comes to what you would actully do. I think flower is easier because the nutrient levels usually don't change much, during veg you want to ramp it up as the girls grow real quick... so you can adjust on the fly... ie add more nutrients to the main rez. During flower you will want to do it like this.
So, let's say it's around week 3 of flower. They will probably be at their peak as far as how 'hungry' they will get. You will have an idea how much nutrients they want from before, for example let's use 1000 ppm. I would think the full 80 gall a bit much with the roots big... not like it's too much, just not all necessary. So say 65 gallons. I'd drain what was there before and start filling up the water. In case you didn't see it there are instructons as to what to add to the water first on the DM site. I beleive you add silica first when there is less than half the water, then zone, add 2.7, and cal-mag when things are more than halfway... then you add the nutes toward the end.
So... I would add the recommended ammount of Silica, Zone, and Add2.7, along with 5-10 mL/ gal of Cal-mag (you should be able to tell what the girls want here to thoughout the grow). Then I would add whatever nutrients to get the ppm to the desired place. (this is something you will need to learn as well.... ie 70 mL of Gold Flower A = around 200 ppm in 65 gal of water).
Damn man... I'm making this sound complicated as hell. It's really not that tough.
So anyways... we'll fill up say 65 gal... and have that sitting at 1000 ppm. Run that for a couple days and check the water level and the ppm. Becuase you have so much water, I expect your plants not to drinnk too much of the volume. I mean I don't think they are going to drink 65 gal in 14 days... or anywhere near that. So a couple days into it, if the ppms are pretty stable, just do nothing. Let them drink. If the ppms are getting higher... dump in more water till you get to say 900 ppm. See what the plants do with that over the next couple days. Basically you want the ppms to be stable.
Say you get exactly how many nutrients they want, so no need to add anything. I would just watch the water level, and if it gets to half of what you put in... like 32 gallons... I would just add more water to finish out the two weeks. If you do get that low it will be close to changing time.
Oh... one thing I forgot... If you are using RO water you are going to need Cal-Mag. I use Botanicare I think. They are all the same pretty much.
I think that's kinda the overall idea. I haven't mentioned pH yet... we'll get there. Let me know if that is unclear.
Holy shit. THATS EXP.............. 
Got lots to learn. I love to learn new shit so its all good. my wife gets a bit jealous of me and my bud porn adiction lol. Peace out 1BMM
...... I need to smoke bro. I'll finish this up in another post. I'm smoking this one for Your hangover... hope you feel better over there.
