As some of you may know I've been struggling with these nutes, not having plant issues, but more with the cost and need for some of these outrageously expensive additives. I used the SH grow nutes and had fantastic success, but I decided to go with something else for the bloom. A neighbor, and several people online here, recommended Advanced, so I went to the grow store, bought a liter each of Sensi Bloom parts A & B and a liter of Big Bud, the guy at the store told me they were the best, and add as much of the Big Bud as you want, there's nothing in there that can hurt you plant.
Okay, the Sensi A & B add up to an analysis of 5.8-6.1-8.8, or 6-6-9, not a bad mixture, Uncle Ben recommends a mix of 1-3-2, not much different really. Adding the Big Bud raises it to 5.8-8.1-12.8 or 6-8-13, getting pretty heavy on the K. From what I've been reading you need more of a balance, yes when you flower the plant will shift more toward needing less N and more P & K, but you still need the N. Now I see where using too much K can inhibit the plants ability to use the N, therefore the yellowing and dying lower fan leaves, they are not seeing enough N. for my first week and a half of flowering I used only the Sensi A&B, no Big Bud, nothing happened other than rapid growth (those following know my plants are doing just fine). Then the last few days I've begun adding the Big Bud, can't hurt right? Well today I am seeing my first fan leaves dying, only two though.
I'm thinking the Big Bud may have overdosed the K and is now choking out the N and that's the reason for the fan leaf dying (only two so far). I still used some of the Big Bud today, but I think I'll stop using it for now until I see what's happening to the fan leaves, at least a few days. I'm pissed I spent the $42 on that one little liter of Big Bud, but everyone is foolish at one time or another.
This nute question seems to be a pretty passionate one, there are those who are insulted by the fact that the high dollar nutes they've been spending their money on are probably no better than what you can buy at Wal-Mart, and they are ready to fight about it. Well, I'm not one of those, I more in the way of being insulted by the asking price for these nutes, damn advertising.
I have a lot more research to do, but yesterday I found a profile calculator to use in determining exactly what concentrations of what nutrients are in any nute you buy. I'd like to do some analysis of all the other nutes in my closet that I've been using on my house plants and out in the yard. A quick glance at one of the boxes of Miracle Grow looked promising. The next question then is how much to use to get what concentration, but that's the reason for the calculator. Here's a link:
http://www.angelfire.com/cantina/fourtwenty/articles/profiles.htm
Hope this helps getting a conversation going regarding the use of alternative nutes, sorry, but I don't want to argue which commercial brand to use, I'm not going to fight with anyone if they want to use the Fox Farm or Advanced or whatever brand, have at it, I hope you have a lot of success. Right now I'm interested in what I can conveniently buy at my local garden store and not cost me an arm and a leg.
Here's an interesting article on how often you need to change the res.
http://www.angelfire.com/cantina/fourtwenty/articles/nutrientsolutionmgmt.htm
Right now the only reason I can see to change the water is to correct the nutrient ratio and air the roots. More on this subject when I know more about it, I'm getting there.
Hope you're having a great day, time for me to get outside, the sun is shining and the weather is beautiful.