@Mjaylover
Ok,,,,,,Here we go.....
Keep the res below 68 at all times. 62 to 68
You say it smells like growth - EARTHY SOIL SMELL? THAT means rot is happening..I see too much brown in the roots pics...This helps lower pH and I'll get into that in detail below.
I don't see what I was asking about in the "black spots" or see the tell table white "slime" around the spots. So good on that...
I suspect you were locking out the Ca with Si at the mix.......Odd though that you get a falling pH as that indicates excess of Ca - Mg - K and NH4........Not the Ca, Mg or K so that brings us back to the Rot as NH4 "Ammonium" (ammonia is the precursor to ammonium and the creation of NH4 from ammonia is increased as the pH drops).....SO, it's a self perpetuating problem as long as the ammonia is supplied.......SO,,,,,,
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One problem could be that your roots are "shedding" more cellulose from the root growth and that is "rotting" and providing more ammonia to fuel the conversion to ammonium and dropping the pH as an ongoing and increasing result.
Solution - Use a "ZYME" product from Hesi (POWER ZYME) or Canna (ZYME)......These are specific spectrum Biologics that actually "eat" or consume the cellulose fiber the roots shed and turn it into plant usable nutrition......Oh course, reducing available ammonia....
Another could be that you are getting a rising amount of root rot that we simply can't see (some area's did look worse then others and can help to explain the oversize root growth as in them being long and not "ball" like in shape) and that is increasing the available ammonia. I might suspect a contamination of equipment for this ongoing problem..Below I will show you how to treat this in this grow....When the grow is over.....Sanitize everything inside and out with a Hydrogen Peroxide solution for sanitizing hydro equipment - You SHOULD be doing this after every grow! How to do that follows too.
These 2 things address the lowering pH and your leaf problems as we already know that are locking out the Ca....
So,,lets work on the ongoing grow first.....
Get some 35 or 40% Hydrogen Peroxide (I prefer the 40%).....Cheap place to get it is a beauty supply store.....they have both 35 and 40 % - get a few quarts or a gallon if you can.
Grow/hydro supply shop will have 35% but their mark up is stupid....Still if you have no other choice DO IT!
Lets work here on attempting to get the roots cleaned and healthy, while cleaning the system a bit too.
We need to make a 3% solution for this (don't cheat and get drug store 3% as it's not pure and contains contaminates that can ruin the grow).
USE GLOVES WHEN HANDLING THE PEROXIDE!
Mix the peroxide to RO water at 11 parts water to 1 part peroxide and store this in a BROWN gallon bottle....
Now dump your res and drain (as best you can) any remaining nutrient solution from the pots. THROW AWAY the nutrient solution!
Refill the res with RO water to your normal level and add, say for you here - 5ml of the 3% peroxide you made to every gallon of water in the res. Run for 24 hrs.....you should be running a cycle every 3 hrs and one at lights out.....
Now dump and refill with fresh nutrient solution and run.......Do this at every res refill for this grow run! (USE THE ZYME PRODUCT!) You could add 75ml of the 3% to the fresh res as an O2 booster and it helps keep the rot away too.
You should INCREASE the air your putting in the res too! You do run an aquarium air pump with a stone in the res right? DOUBLE THAT AMOUNT!
Now at the end of the run. You need to REALLY clean the system!
Add 280ml of the peroxide (40%) to every gallon of water it takes to run the system at bare minimum to fill the pots and run that for 6 hrs.....spray this mix at any level not reached by the sanitizing solution on your system inside and out (use gloves again!).
Use bottle brush's to do tubing as best you can and scrub out pots and res too...
Rinse with clean RO and start your next grow.....
I think this will solve your problem.....IF between the the first and second dump and peroxide run the browning does not stop...Increase the amount of 3% in the "wash" to 7 1/2ml per gallon.....
Let us know if this helped out OK?
I think it will!
Doc
I really stayed at home longer then I intended to do this - but I promised a solution and I don't brake my word......I'm off to my harvest work....
GOOD LUCK BRO!