Hi JZ,
I haven't had time to post/read much lately...but had to reply on this subject, I agree with the need for TDS and pH meters...I only used a pH meter in the beginning but I feel the TDS meter gives me a better idea of what they are getting...thanks to 420fied
I use the one that someone sent you a pic of...I think it was Mr.K.
for instance, when I make nutes for my hempy 2L's I do something like this...
start with RO/tap @ 60-80ppm, this way they get some Ca (and other stuff) that is naturally in my tap water, and this mix always has a pH around 7.0 - 7.1, then I add whatever nutes I'm going to feed that day (I have to water daily) almost always includes the GH floranova bloom that I'm currently using (I give just RO/tap every 4th or 5th day, depending on what the girls look like) I mix the RO/tap/bloom to 1000ppm (right now @ 20 days 12/12) this starts out about 300-400 when they are little and increases as they grow...I have found with my Wonder Woman they can take as much as 1300ppm late in flower stage before showing ill effects of nute burn.
I use 420fied's schedule for feeding and adjust to how the girls look...wk1-450ppm, wk2-700ppm, wk3-900ppm, wks4-10-1100-1400ppm.
Now...like Mr.K said...you take into account the total ppm's. when I add molasses to the mix I have to use a little less GH bloom or I'll go over the total ppm's I'm shooting for. I find 1 T/gal molasses adds about 100ppm to the total ppm's and raises the pH by .2, I'm sure you'll find your mixes to be a little different but after much testing and retesting you'll come to know what adds how much.
I only learned this with much help from others here @ 420mag and lots and lots of testing :icon_roll
for instance today I gave this...1/4 gal tap and 3/4 gal RO = 1 gal of RO/tap @ 62ppm/7.0pH, then I added 1-1/2t bloom to get 877ppm/5.4pH, then I added my molasses mix (3/4C RO/t heated to boil + 1T molasses) this gave me a total 987ppm/5.7pH...that's what I fed them today...tomorrow I'll do it all over again...because I mix my feed by the gallon, I'm not sure how this will differ from your res mixes but I'm sure it's gonna be something similar only on a bigger scale, maybe I'm doing this all wrong, I'm so new to growing that I probably shouldn't be giving anybody advice...but you asked
and my girls are growing pretty good...although I think I still have my own issue with nutes/pH by the way they look...just keep experimenting, you'll get it
This was so long winded...I hope it helped.
Also, I don't know about the .500 or .700 scale on the TDS meter that Bassman was referring to...this is something I'll have to look into
great...more research
BTW...If you have the time, come visit my journal...I have 1 each PE and OG kush x ultimate seedlings growing right now