I'm growing under one of the LED's, Advanced Platinum Series P300 300w, and a Emily's Garden with a 4 gal reservoir. The light is set at 18" above the seedlings. I have the pH Test Kit (I know, I know - but I can't afford anything else right now). I fill it with distilled water and add the recommended measure of FloraNova grow to it. Every day I test the pH, and every day it is extremely low, -4.0 and down. I put a couple of CC's of General Hydroponics pH up in the reservoir and the pH goes back to normal, but the next morning, the pH is down again. It seems to be down the same amount every time, by my imprecise measurements. The growth is stunted and slow. The bottom leaves are yellow. This is the first time I'm growing under the LED's. I've grown under the MH lights before and it was fine. I washed out the reservoir, again, with distilled water - no result. I changed my brand of distilled water - no result. I've changed the reservoir three times - no result. What could be happening to the pH every night? Or is it just a symptom, something else is going on?
Hard to tell in that light but there looks to be a bit of twisting in the leaves....more than likely a ph issue. Ive never done hydro though so cant help as so the reason for the drop off.
As plants absorb nutrients the ph will fluctuate. It though appears something else is affecting you plants. How old are they and what ppm are they being fed.
I'm feeding them 1/4 tsp per gallon of Flora Nova grow. I'm still at a loss as to what's fluctuating. I wish I could afford a pH meter or a PPM meter - but I can't. I'm trying to get by with pH test kit and measurements. As you can see, two plants are growing now with DARK green color and all the other ones are still stunted. I've narrowed it down to something in the nutrients; either something that's literally in them or some kind of way they react. I fill the reservoir up with distilled water and it stays stable. When I add the nutrients it gets unstable. I got seedlings on December 10th 2015 and this picture was taken today.
we have been using adv nut ph perfect for coco and we havent had to add any ph down or up we change reservoirs every 7 days. So far so good. Ph on our regular water is 7.8 and we down it to 5.8 (a little lemon juice) and it has never gone over 6% in 7 days all but once its been at 5.8% when we change em up
Nutrient levels are too high, the plants are taking up more water(higher in pH) leaving more nutrients(lower in pH) leaving the solution a lower pH as a whole.