PPM in DWC

[Bigpapa]

Greetings fellow growers.

I’m on grow #8. I think I have what I do down pretty much. My yields are very satisfactory and potency has been excellent. Best result, 29%. Lowest, 19%.

That being said, now I’m trying to really micro-manage my latest project. And that gets me to my question. Using RO water that is 15 ppm, with GH Flora Trio in conjunction with CaliMagic and HydroGuard, what is the exceptable range for ppm? Changed out my nutrients today and when all was set, my ppm was 470. PH, 6.0.

DWC - 5 gal. reservoir with 3 gal of solution.
600 watt MH and HPS. Using 2 COB LEDs to augment HPS during flower.
4 x 4 x 80 tent.
Growing 1 plant at a time.

[furrysparkle]

You have my ideal setup when I get my own place, please photos, and yield weight with each strain, if you can of course

[9fingerleafs]

I’d say you’re on the low end of the spectrum. I feed my soil girls with 1000ppm or 2ec every watering and they love it. It depends a lot on the setup and I don’t really get what you mean by acceptable but it’s not crazy low and definitely not high. You gonna have to ask your plants haha

[Cloud]

I'm at 650 ppm with similar grow method and nutes. Rises to 850 before nute change.

[IGH]

a plants ppm requirement is irrelevant to which media or nutrient line you are using. your light/watt equivalent and canopy volume determine how much nutrient can be safely processed.

i have found that as a rule of thumb the ppms should not exceed the watts (or equivalent for LED) of the light properly distanced above the plants.
in this range the plants cant burn from too much feed, and neither do they become defficient.
yes, some strains are hungrier than others, and this calculation method gives results slightly on the low end. so after observing thier growth and are convinced that a little more ppm would be beneficial, you can raise the concentration 50-100 ppm per week-10 days safely, just be sure to monitor plant health closely during the process, roots included. too high of a concentration also burns root hairs.

i know its a different way of seeing things, but the concept is simple, logical, and backed by science not by product marketing or some secret recipe.

my own experience, 6 grows. first 3 feeding schedules based on GWE schedule and what others said they used, with mixed results, good yield and potency, just cost some time with minor issues causing veg times to go long. after using the ppm calculation method i described above i can now FILL a 4x4 DWC space in 8 weeks with 4 plants that never burn, stall, or go defficient, plus, naturally weight and overall quality increase because the plants dont waste time, energy, or resources on stress and repair!

hope this was helpful. keep raising the bar!

[furrysparkle]

My same comment to you, if you can, weights for each strain you’ve grown, light and what’s your hydro design

[IGH]

furrysparkle i have yet to get less than 1 lb in a 4x4 under 600w, and 1.5 lb in a 5x5 under 1000w. all my strains are pure indica or heavy indica hybrids, and different every time.
and im a chronic builder, 3 systems to date and ive already started purchasing parts for my next...and last for a loooooong time. i started with 1 40 gal dwc res. scrapped it after 1 grow. built 2 18 gal dwc res used for 1 grow. took those 2 made 2 more and i now run those 4 RDWC. currently building a 12 site rdwc so i can cut my veg time in half, and equipment usage by 30%.

[furrysparkle]

Each system supports one plant in an 18 gal container? 10 gal of water?

[IGH]

each system has 2 18 gal reservoirs. about 20 gals nute mix for 1 system.
1 system has 4 sites for long veg big plants, the other has 8 sites for more medium sized plants and a shorter veg.

[Friedumpling]

I read somewhere that if you use a PPM meter, you can really dial in your perfect PPM for your given setup. Since different strains respond differently and even the environment can change the PPM required, it made sense to me.

The main idea being that the plant will consume the right amount of nutes regardless of your PPM. But, if your PPM is too high, it won’t absorb it all, which in turn makes your PPM go up. This contributes to nute burn as your PPM could potential sky rocket.

On the the other end, if the nutes are too low, the plant will drink more nutes than water making your PPM drop off. Eventually turning in to a deficiency.

Measuring PPM once a day (preferably at the same time) will help you monitor the PPM uptake. If your PPM has gone up, you refill your bucket with plain PH water. If it goes down, you refill with water+nutes.

Example:

refill my bucket at 1000 PPM
24 hours later, PPM has gone up to 1100PPM. The plant is drinking more water than nutes, refill with only water to drive PPM down to 900PPM.

Example 2:

refill my bucket with 1000PPM
24 hours later, PPM has gone down to 875PPM. The plant is hungry for more nutes than available in the bucket. Refill with water+nutes to keep PPM up.


If the bucket is the same PPM everyday, your plant is drinking the right balance of water and nutes.

Either I have been lucky, or this method actually works.

[IGH]

and you never burn the tips or see deficiencies in your grows using this method? sweet. what about your harvest weights, measuring canopy volume to light watts? cuz thats where it matters.

[FlyingDutchPaddy]

Hi Friedumpling,

Would you by chance have kept an eye on what the pH of the water was doing in your 2 examples, and when the PPM stays the same?

[Bigpapa]

Hey Friedumpling, finally a formula that makes sense. I think I’ll give it a try.

Exactly what I was looking for.

Thanks.

[Friedumpling]

Nice tent!

[Bigpapa]

Thanks. So I’m clear on this technique, contrary to the GH instructions, instead of topping off during the week with plain water I’ll be topping off with whatever week I’m in’s proper ratio as long as my ppm remains under 600 since I’m under a 600w HPS. Is that the general idea?

[DankwingDuck]

I would keep it under 600ppm for veg and no more then 1000ppm in full bloom

when I start my dwc it starts at 50ppm and I work it up to about 550 for full veg

then transition nute are 450ppm and then that works up to about 950 for full flower