Here is a great short tutorial about mixing nutrients. He uses the recommended concentrations of a specific brand for hydro, but in general and regardless of nutrient brand and the mixture ratio/concentrations may be different but otherwise there is some good advice that should be used whether mixing your nutrients before pouring them into your hydro reservoir or pouring them on soil or over your soil-less media.
I’m thinking waiting as long as he did between adding new nutrients was a bit excessive, the main thing being you mixed it in the larger body of water and thoroughly mixed it before adding the next one. This goes for adjusting ph as well. I also thought the fresh lemon squeeze to adjust the de-chlorinated tap water to below 7.0 was kinda neat. Pure water is almost always 7.0 and purified water and most bottled water are always pretty close to neutral in pH, however some bottled water and tap water is often a little on the alkali side, 7.5-8.5. Too acidic of water is not good for plumbing, and too alkali of water is often a result of “hard water” and results in too much mineral deposits in your plumbing fixtures.
Good Info. I have written an article on this and it is posted @ Cannabisdotcom; At the top of the hydro section. 
It is no longer there; They must have realized i was using the site for storage LOL. I copy my old text, and paste it into new forum and copy link location, but now I have to find the link…Eeeee 8-O
Only thing about the video; I do not agree with is adding epsom salts - Magnesium Sulphate is already in the 3 part. predominantly in the Bloom; Which he cut back. If you just use the full 40ml for bloom also; Then there is no need for adding “MgSo4”
Not to mention he added Cal Mag. Be careful not to keep adding the same minerals when you choose to add booster, and the like. Good Luck.
p.s. I am looking for my article. Meanwhile I am rescuing all my articles from Cdot before they disappear altogether; So; I am @ latewood.com building my growfaqs, then later to here as articles. If you need me; Skype me @ IMLatewood
He did mention Magnesium was in the CalMag supplement, so I too felt it was kinda redundant but apparently it’s working for his lettuce greens. As I noted, different nutrient brands/systems will be different in the types and ratios of the mixes. But the way he measures, keeping all parts separate until thoroughly mixed in the larger body of water is great as well as his advice about de-chlorinating your tap water for those that insist on doing so, this too could be a matter of argument as I’ve seen plants grown healthy either way, straight from the tap or after letting sit out and/or aerating the water to purge the chlorine gasses out. One other thing I would have done different as well, is start with the cal/mag supplement, be it CalMag+, CaliMagic, or the Epsom salts( MgSO4·7H2O). To each his own and yes, Good Luck in your grow!
You monly need to mix additives 1st, when you are attempting to acheive a target ppm. The point is; You want a target ppm of 1200. So; You add additives 1st, and then equal parts of your base nutrients until you arrive at 1200.
Although it is good advice to wait after putting each part in the water; Unnecceary. Once you put the base mutrients in the water a stir; You can add the next part. You do not need to stand around for 2 minutes after each part.
Not only is MgSo4 in the Calmag; It is in the 3 part also. I used GH 3-part for about 4 years. I have always used 8-10ml per gallon. I use 1-1-1 for grow; Not 1-1-.5 as he does. The Bloom also helps to make the roots stronger. This is because of the potasiym. After 2 weeks in flower; I change to the Lucas style 0-1-2.
I have got to find that Damn article I wrote years ago.
