pH 7.0.....EC 0 rainwater as you know. I'm just about to mix up another 40L!
Alls looking well, tee mate, was wondering, re your water regime............
The 40ltr res water is stored in a single 50ltr open top bucket ? as it's rainwater, you do not ever have to worry about aeration !! it's perfectly saturated with 02, co2 and nitrogen........ how do you raise under house water tank temperature to within 2c of root ball tee ??
Put res bucket In the room, with the air-con going, so room and tent at 26-29c...... so the base water is within 2c of the root temperature, in the tent tee ?
4 plants, so 10ltrs fed to each plant every day ?
letting them dry out just once in 7 days tee ?
Do you make up the base "Rainwater" Ec0.00, with a buffering solution, (As It's Ec0.00) to 150-200ppm ?
Only you can also use b-carb for this, 'zero salt rainwater "Buffering" as it, bi-carb, it accepts cation ions H+........ so is a good source of alkali salt for buffering RO or rainwater....
So at the moment no buffering added, you just make up your "Built" nutrient profile, in the 40ltr reservoir, add the appropriate Ph up or down, dependent on nute Ec strength, macro-nutrient profile, etc... and feed em,
10ltrs each ?? 'FRESH MADE" Built / Crafted, Nutrient Solution?
every day....... say 5ltrs morning time 5 in the evening's tee ?
As we know at the moment your feeding an alkaline dominant feed, to raise the low Ph of the over-washed, acidic, duff cocco batch,......... so you are adding alkali (Molar), b-carb, which also is = to a pure water (RO) & (Rainwater) buffer, which is aiding recovery..........
You use silicone Ph up under normal circumstance then tee ?
i have what i realize now is a luxury of "Very Hard" tap water, TDS=450-520ppm, would give you kidney stones in a week !!............ but it is brill for adding to my zero salt rainwater, as a buffer........... so i mix 25ltrs every other day, fresh built nute set, warmed to 3c above root temp..........
As my nutrient strength (Ec) begins to climb, through the grow, i add more and more buffer to the 25ltr res. This off sets the increase in acidity, due to more nute going in !!............ i tune in to this, to a point where i dont have to add Ph down, i just withhold the buffer ltrs to suit, so i dont add any Ph down.
Accordingly, during last 5wks of fruitification, i like to feed @Ph7, this aids the buffer, and off sets any acidic nute build up, "After" the mid term 1-2 days zero nute flush, to reduce this effect......... checking at this stage what run off feed back is telliing me............. a 3 way triangle, soil Ph, nute acidity, and water buffer combination. Which shifts alkaline at the end of the grow to aid trich formation, and promote pk & ca uptake.................