Help with EC please!

Hi,

1. The Canna Coco schedule I have tells me to add 2.3 ml of A and B Coco nutrient to one litre of water at ph 5.8, so I added a total of 4.6 ml to one litre of water.
2. The schedule gives two EC values, EC+ 1.1 and EC 6.9 but I don't know which value to use.
3. When I tested the nutrient solution mixed as above I get a reading on my EC (uS/cm) meter of 3300, which equates to EC 3.3 (mS/cm).

I thought EC is controlled by adding or taking away nutrients so have two problems.

a. Which is the EC value from the schedule I should be targetting EC+ 1.1 or EC 6.9?
b. I am of the understanding EC values are changed by adding more or less nutrient. If so how do I reach the recommended EC value without reducing the recommended 2.3 ml of nutrient?

Did you take into account the EC of your starting water? Also, you add nutrients and then PH since the nutrients are acidic. If you PH first and then add nutes your ph will be too low.

Just mix your nutes at 1/2 of whatever the manufacturer says, take an EC reading and then later adjust when the EC has dropped more than say 30%.

The answer to B is... you don't/can't short of say adding salt

Thanks, I see what has happened now I've read your posts. Instead of chosing hard or soft water I did do the right thing and EC my tap water however I put in the figure '10' instead of '1.0'.

My tap water has an EC of 1.0 and a PH of 7.2, what is RO water?

ukdave said:

Thanks, I see what has happened now I've read your posts. Instead of chosing hard or soft water I did do the right thing and EC my tap water however I put in the figure '10' instead of '1.0'.

My tap water has an EC of 1.0 and a PH of 8.2, what is RO water?

Click to expand...

Reverse Osmosis or finely filtered water. Yours is too high. Is it well water? I never heard of municipal water at EC of 1. In any case when you mixed again did you get an EC of 2?

read this thread about water : https://www.rollitup.org/general-marijuana-growing/294579-water-most-essential-compound.html

Here are the results from the begining.

Do it over in these steps:

1) Get the EC and PH reading of your raw 1 liter of water.

Click to expand...

EC = 1.16
PH = 7.2

2) Add nutes

Click to expand...

Added 1.9 ML Coco A and 1.9 ml Total 3.8 ml

3) PH to 5.6 or so.

Click to expand...

PH'd down to 5.8

4) Take EC reading, it should be 1.1 or so plus the reading obtained in step 1. (provided you didn't dump a ton of PH up or down)

Click to expand...

EC reading before PH Down: 2.54
EC after PH Down: 2.74

According to the coco schedule generator with a 'normal feed' setting I should have got an EC reading of EC+ of 0.9 and a total EC 2.1. My final result was EC 2.74, is there normally this much of a difference?

It looks like an RO water filter/pump would be a good idea in any home with water as hard as mine.

Your water EC is so high I wouldn't expect textbook accuracy. Without you knowing what constitutes that high EC, it would be safer in the long run to get filtered. Try your ec experiment with distilled water if you are curious to see the expected EC readings using clean water. Those nute EC/PPM numbers from manufacturers aren't always spot on. Good luck. I like that canna, coco rules.

Edit: Sometimes it's better to do a test of this sort using more water, say 4liters, less margin for error

I appreciate your help, and probably will experiment with distilled water now I'm a little more informed.