The nutrients will change the pH of the water regardless of the source, ideally you want to be able to measure and properly pH your nutrient solution. A decent pH meter is an essential tool for growing.
These are the exact steps I take to properly preparing a nute solution:
Note: My res is 25 gallons, so you will have to adjust all volumes for your res size.
I would suggest getting a container that would be able to hold the same amount of water as your res. That way you can prepare your mixture in the mixing container, then empty your rez and immediately pump the fresh solution into your system so that they will be out of the water for a minimal amount of time to reduce shock.
# Use good water. I use RO (Reverse Osmosis) water.
# Add all of your "extras" to your reservoir
In bloom, I add 80ml of Bcuzz bloom stimulant (Bcuzz's suggested str for 25 gals), and a small amount of Epsom salts, about 2 TSP (10ml). You must mix your e-salts in warm water, or they will take forever to dissolve and throw off your readings. This little trick will help you whenever you need to mix something solid into your nute solution. Dissolve it first.
# Nutrient mixing.
What I do is get a gallon of water, and mix my nutes ratios into that container, then I simply add that solution to my res until I reach the desired ppm. You CANNOT mix them together in their pure form, they must be diluted or nutrient lockout can occur. I never pour nutes directly into the reservoir.
My system holds 25 gallons, so I use 80ml as my "base unit" of measure. I use the 1-2-3 (G-M-B) formula. It is the one that GH recommends and it works well for me. For example 1-2-3 = 80ml — 160ml — 240ml
# Always add Micro, then Grow, then Bloom.
In my bucket of water I add 2 measures of GH Micro. Mix. Then I add my 1 measure of Grow. Mix. Then I add my 3 measures of Bloom. Mix.
My measure is 80ml - yours will be different according to your res size.
# Use a submersible water pump to keep everything mixing in your main rez.
# Add the GH mixture slowly to the mixing container until I reach my desired ppm. After I have the ppm's set, I adjust my ph until my mixture is perfect. Then I quickly dump my res and put the contents form my mixing container into my res.
Be sure your nutes are fully mixed before trusting your readings. I have found ph to take longer to stabilize than ppm's, so allow the tank to really mix up well before you count on a ph reading to be true.
Here are some GH ratios I use:
pure RO water and a rooting powder, liquid, or gel is all you need
Seedlings / clones
Add a drop of superthrive per gallon of water, e-salts, and a 1-1-1 (G-M-B) GH mixture at 250 ppm and adjust ph to 5.2 — 5.8.
Add a drop of superthrive per gallon of water, e-salts, and a 1-1-1 (G-M-B) GH mixture at 350-450 ppm and adjust ph to 5.2 — 5.8.
Add a drop of superthrive per gallon of water, e-salts, and a 3-2-1 (G-M-B) GH mixture at 500-650 ppm and adjust ph to 5.2 — 5.8.
Transition to blooming (first 2 weeks of 12/12)
Add my Bcuzz bloom booster, e-salts, and a 1-1-1 (G-M-B) GH mixture at 700 ppm and adjust ph to 5.2 — 5.8.
Add my Bcuzz bloom booster, e-salts, and a 1-2-3 (G-M-B) GH mixture at 750 - 950 ppm and adjust ph to 5.2 — 5.8.
When I give a range of ppm, I start off low and mix a little extra GH to slowly bump up the ppms as the days go on to make sure the plants can handle it. Every strain will grow a little different.
If system heat is a problem, you can use a silicone solution such as pro-tekt (or Pro-silica) to raise ph and give the plants a little something to help them out in hot weather. Use it sparingly. I wouldn't add more than 1 ml per gallon into your res. It may slow down growth.
Don't try to add all kinds of stuff to your res, the simpler the better. That is why I add so little Epsom salts. If I start having Mg issues I would bump it up, but I haven't had to yet.
You will not need H2O2 (hydrogen peroxide) unless you have an improper nute solution. If you keep your res temps at 68-72* and it is light tight you won't have algae problems and your plants will be the happiest. The higher your nute temps go, the less O2 the water can hold. It is a property of water itself and no amount of bubbles will help.
I keep my nutes at a ph between 5.2 — 5.8. If it is in this range DO NOT try to get it "perfect" by adding ph up and down.
If you mix up your solution and you don't HAVE to use the ph up or down DON'T. When you do adjust try to hit 5.5 but once again don't be too picky. If it's a little higher or lower let it go. You'll just mess things up by trying to mix it exactly.
If you have a nutrient deficiency, or some other problem that you think might be nutrient related - change your nutes!
Some members prefer to add main nutrient components first, additives later:
(~shabang~) "Anything organic will throw your EC/PPM measurements off and it will be harder to judge how much salt fertilizer you've added. I've always thought it best to put the additives in last after you're happy with the chem levels."
Be careful when mixing highly concentrated nutrients, as lockout can occur when adding pH "up" (As may occur in a smaller volume). It is my experience that K can precipitate out of solution - make sure pH "up" or "Down" is added to the nutrient solution with additional water).
Another mixup procedure is to mix the nutrients directly into the main rez. This method takes longer, as adjustments require additional mixup of seperate nutrient components.
(Reggea love) Nutrients strengths should be qualified with the ppm/us conversion factor used (such as 0.5, 0.6 or 0.7), which can make a significant difference to the actual strengths.]