Nutrient Application & Watering Schedule

[Ganja Goose]

Hey 420,

Hope everyone is staying safe. This post is follow up to a pervious post of mine - Nutrient Advice. I hope it's okay that I started a new follow up thread as I wanted to start a new discussion based on what I think I've learned in the old one vs. getting lost in the tangle of another thread.

I run a Promix medium and I use the Advanced Nutrients 3 part system with some of the supplements they recommend. Nothing fancy. I am a few weeks into my 3rd grow and I've switched from some nasty tap water to RO water for this grow, which seems to make a big difference this round with fairly healthier looking plants. From an EC perspective, I'm feeding about 1.2 at the 7 week stage in VEG. I have also recently switch from CFL to LED so I'm expecting things to possibly ramp up in that department.

First question - I recognize that there is an opinion out there that measuring run off and adjusting feed concentrations is not recommended and that my Promix soil contains a certain EC right out of the box so its not really applicable. But If I measure the EC of my plain Promix (it's runoff was 0.6) can I not use that as a baseline for determining possible adjustments on the input side? 0.6 would represent zero nutes in the promix and some adjustments upward on the next feed would be required?

Second question - the process of measuring runoff and making adjustments in the feed EC seems to make sense to me in theory for the most part. Ignoring the Promix 0.6 EC for a moment - EC in runoff is lower than my input EC thus equates to plant is taking in nutrients and adjustment upwards of EC required for future feed. EC in runoff is higher than my input feed than I need to decrease future EC. That said, I would have thought if the runoff EC matched the input EC then everything is good, but I've read in multiple threads that this is not a desirable condition?

Third question - lastly, I've learned how to water correctly (thank you @Emilya) ensuring the pots are completely dry before watering. I am even using the frequency of watering to determine when to up pot. I am still confused on to manage watering schedule in relation to feeding schedules. How does one account for the water only schedule on the EC of the feed schedule? Measuring EC runoff seems to only make sense if you're feeding nutes every time. Watering on its on would impact the expected EC from runoff no?

Again sorry for the long winded questions, but as a newbie grower I'm pulling in all the information I can from everyone and trying to navigate my way through. Hopefully future questions become shorter and more concise lol

GG

 

[Fuzzy Duck]

Don't blame the tap water over RO water when you have recently just changed from CFL to LED to noticed plant health big difference in light spectrum between the two lighting sources !

The rest of it is, over think maths...

 

[Ganja Goose]

Don't blame the tap water over RO water when you have recently just changed from CFL to LED to noticed plant health big difference in light spectrum between the two lighting sources !

The rest of it is, over think maths...

Hi @Fuzzy Duck

Agreed and my apologies for not being clear on that particular time line. I had made the switch to RO at the beginning of the this grow (8 weeks ago) and saw much healthier plants in VEG. The switch to LED happened yesterday.

....and yes there has been lots of thinking going on LOL

GG

 

[Ganja Goose]

Hmmmmm........I wonder what happened with my post such that it didn't receive any attention? Help please

 

[Weaselcracker]

I read it at the time. I’m sure others did too. It’s a lot to read and decipher and try to answer. Mostly I think it’s overthinking it and better suited to a pure hydro grow like DWC where there’s no intervening medium. Something like Promix retains nutrients for quite a while, as well as containing its own ingredients- lime/peat. It’s not totally inert.

In a pure hydro medium you could measure any changes as they occur. In Promix measuring runoff is unreliable. Maybe you could make it work. But it still seems unnecessary. Most people prefer to just watch the front end and monitor what they feed the plants, and see how they respond, rather than trying to measure what comes out the back end.

You’d need to develop a consistent system. How would you measure runoff reliably? Evaporation rates will be different on different days and make the mix in the pot vary in concentration. The EC of the runoff will never be the same at any given moment as the new water/nutrient mix washes through and dilutes whatever it finds in the pot. Will you always measure the same quantity of runoff over the same time period in an effort to make the results mean anything?

I’m getting a headache thinking about this...
But then I don’t water my plants ‘proper’ either

I’m sure you can do this and maybe it’s easier than I’m making it seem. I don’t know. No one is doing it this way as far as I know. I would suggest a truly inert medium if you’re going to do it this way- something like rockwool or coco would work better - though still with difficulties. I’m wearing out my typing finger...

Good luck