Water quality problem in veg phase?

Hi everyone!

I’m reaching out because I’m having a tough time with my cannabis plants, especially during the vegetative phase. I’ve been reading on Rollitup for years, but this is my first post. I hope you can help!

Here’s my situation: since moving to a new place and switching to coco coir, I’ve been struggling to grow healthy plants in the early stages and during veg. They seem to do better as they approach flowering, but the stress during veg is really frustrating. I’ve also noticed that my LED lights seem to be particularly harsh on the plants, making it hard to grow under them.

Here are some details about my setup:

• I’m using Canna Coco A+B nutrients and growing in a 70% coco/30% perlite mix.
• The coco is pre-buffered Canna Coco Pro.
• I keep the pH between 5.8 and 6.2.
• I hand-water slowly to achieve about 20% runoff, but flushing often stresses the plants.
• I’ve tested various distances between the lights and plants, but I still struggle.

Interestingly, during flowering, I end up flooding the plants with nearly 100% runoff, and they seem to thrive. However, if I try to reduce the runoff to the normal 10-20%, the plants react poorly.

I’ve tested everything I can think of, including different runoff amounts and nutrient strengths, but nothing seems to work. I’m starting to suspect that my tap water might be an issue.

My tap water has a hardness of 340 ppm and a pH of 7.4. I have a reverse osmosis (RO) filter that produces water with 35 ppm and a pH of 7.0. The calcium to magnesium ratio in my local sources is about 9:1, while I’ve read that a 3:1 ratio is ideal.

Could this imbalance be causing the issues I’m facing during the vegetative phase?

Below is a table with average values for different elements, taken from 8 months of data, for the area where I live. For those knowledgeable about water quality for cannabis, could you let me know if there’s anything that stands out?

Should I stick with RO water and add cal-mag? I’ve tried different ratios of RO to tap water, some work better than others but all work poorly.

Any advice would be greatly appreciated! Thank you in advance!

How often are you watering, and are you always using nutrients when you do?
What is the EC of your feed?
What model light, height from the top of the plants, and dim setting are you running?
Pic of plants?

Coco is pretty straight forward: Feed with nutrients at least once a day (never give plain water) to at least 10% runoff with a veg EC of 1.0-1.2 (500 to 600 PPM on the 500 scale).

As for water, I use RO because my water is hard and it gives me more control. That said, if the water doesn't make you sick when you drink it, the plants probably don't mind.

Why are you flushing?
Are you using plain water when you flush? Never use plain water.
Flushing shouldn't be necessary if you feed daily to substantial run off.......it prevents salt build up.
I have never flushed.........and I've been in coco for decades.