I need help understanding how to check run off and what it means

Ok so I’m having a hard time understanding something I’m sure is simple to some but this is my first time and frankly it’s kicking my ass! I’m useing Bergman’s nutes and properly measuring, chart says ec should be 2.5. So my question is, does this mean 2.5 runoff? I checked my runoff today and it’s 2.7, so do I keep giving ph balanced water until my ec runoff is below 2.5 and add nutes again? I have been fighting some kind of deficiency(s) for weeks now(had thread started) and I just want to understand how to check ec? I think I have the ph down, although I was useing ro water and adjusting ph but was told ro doesn’t have ph, so now I’m just going back to tap water and adjust my ph lol

I’m useing the blue lab combo meter and I’m useing soil not hydro.

Please help me understand, I don’t wanna be stressed this should be fun.

This is the EC of the water you are feeding, not what’s coming out.

Nope. The idea here is you will water normally (EC 2.5 and pH 6.5Ish) regularly with about 20% runoff every time you water.

The only time I take a moment to check my runoff numbers is if something is wrong with my plant and basic troubleshooting hasn’t helped (reviewing notes and checking my NPK ratio is still in line with my expectations of what I thought I was giving her). You can generally assume that if you got it right going into the soil, it will come out “close but not quite.” Runoff will always be a little off from what you feed, because your plant will eat and leave behind salts in the soil that rinse away in runoff and throw runoff numbers a bit out of whack from what you’re putting in.

EC/tds/ppm is all the same information, more or less, just different scales to talk about the same thing.

With tap water, I recommend checking the EC first before you add anything to the water. Take note, then add your nutrients. Take note of the final EC reading. Let’s say your tap water is 0.8 EC, and your final mix of nutes is 2.6 EC. I subtract my tap reading, because I just don’t know what’s in it.. 2.6-0.8 = 1.8 EC. You may be unintentionally undersupplying the nutrients she needs, thinking you’ve mixed it to the strength the feed chart calls for but not accounting for the EC in your tap water.

Agreed. Just worry about what’s going into your soil - make sure it’s within the ballpark (if Bergman says 2.5 EC, I’d be happy between 2.3 and 2.5) and feed.

As an aside, be sure you’re dechlorinating your tap water some how before use. It may cause harm to hit it with high doses of chlorine or chloramine.


So if I’m useing ro water I don’t need to check ph or ec as it has none correct? I only need to check runoff so I get an idea of when to add nutes again? Thank you

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You’d be okay in terms of ph but you’ll need to add cal mag eventually as it doesn’t have any. From what I understand during the veg cycle you can get away with having a wider ph range because the primary nutrients can be absorbed in a wide range but as you switch into bloom/flower you need to be more dialed in to be able to access those nutrients properly. I’m a new grower so take what I say with a hint of salt but I’m sure they’ll correct me if I’m wrong, or just go more in depth than I can.

This gives you an idea of what you’re working with.

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I wanted to clarify to help you on what you said about RO water. Distilled water is neutral at 7.0 ph. RO water can and does have a ph. Reverse Osmosis and distillation are 2 dif processes. I use to use distilled but became too expensive. I now get 5g ro for 1.00. I always ph everything going in and my ro is from 7.3 to 8.1. Check urs and let us know


Exactly! It’s about 6.9-7.0 then I use ph down to adjust to about 6.2-6.3

I’d direct you to cocoforcannabis.com. You’ll find everything you need to know about pH, ppm, EC, runoff, etc, what it all means and what to do with the numbers. It’s written in a way anyone can understand. Do some reading there. You’ll be glad you did.

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Thank you I really appreciate it

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Kinda false - you gotta check the EC after you add your nutrients. Always adjust pH and PPMs to fall within range before you feed.

Right. Or to see if you need to correct your pH - if it drifts too far up or down, you’ll want to adjust the pH - which means adding something (CalMag is good) to give the RO water an EC Value. You can’t measure the pH of ro water because it has nothing in it.

I don’t think that’s true. No disrespect intended, but anything with fewer than 100ppms does not contain enough of anything to accurately assess the pH. Your meter will still give a reading but it’s not going to be accurate. Distilled and RO, if properly filtered, should have 0 PPMs and will be true neutral. Once exposed to things like air, or your soil, they adopt the pH of the medium and will also help get a realworld idea of how much nutrient is remaining in your soil/medium.

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One of those agree to disagree things.

When I worked in the lab we made ultra-pure water for preparing standards for trace level analyses. Difficult to measure hydrogen potential (pH) when hydrogen and hydroxyl ions are balanced (no potential).

We measured resistivity and 18.2 was the magic number.

Enough nerd talk for the day.

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Distilled water in a closed environment is neutral with a Ph of 7.0; when exposed to air the Ph starts to drop. For most applications one can use Ph of 7.0.

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