Flushing Cannabis- Removing the "Bro Science"

Everyone has a different way of finishing their plants, often with flushing. Excess phosphorus and magnesium in finished product can give off flavors or make flowers burn black. So what’s the proper way to flush a cannabis plant?

One common way of flushing is with RO water in hopes that it will leach nutrients from your growing medium leaving a cleaner product. Using RO or soft water may actually strip electrolytes from plant cells leading to lower flower weight or terpenes that evaporate more quickly. This is the opposite of the desired outcome when growing.

So what is the proper way of flushing? Osmotic pressure. It can be an inert substance like glucose in commercial clearing products like Clearex. It is a low EC solution allowing the plant to mature properly while maintaining plant cell and trichome integrity. This leads to more weight, a wider window for curing and more residual terpenes.

What other products can be used for flushing plants?
-Glucose, sucrose, fructose
-Compost or worm casting tea
-AGT-50 Fulvic Mineral Complex (Which also allows nutrients to be used up instead of simply washed out)
-Hard well water (as long as it is low in magnesium)

I always tell everyone I want them to have the best possible grow, and flushing a plant is a big part of that.

For further reading on osmotic pressure, please read:


Manic Botanix (Scroll down)


Awesome post @AgTonik im a big fan of glow as u know! I remember when he was on the forums it was a hoot watching his interactions huh?!


So normally in our rdwc system I flush with straight RO water. Cultured solutions recommends their UC roots (hypochlorus acid, I know you know, but just so the content is in the up and up). What would you suggest in a system like mine?

I suppose I could introduce agt-50 if it’s just straight RO…


I would love to see this. How long do you usually flush with ro in your rdwc?


I flush the system 3 days in a row to get the residual ppm level down to 0 then maintain that for 3 days.


I think it is clearex that a friend has used before, and it makes the bud smell and taste like fabric softener. It gets worse over time as the harvested bud ages. And this is with aeroponics, idk if that makes a difference.

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Grant “GLOW” is a friend of mine and we chat about once a month. Some folks have a “stage persona” when it comes to the internet, but he is seriously one of the top 10 cannabis agronomists in the world.

The sodium in hypochlorous acid works as an electrolyte, and thus a flushing agent, although I wouldn’t be mad if you used AGT-50! :kiss:

I know they use a bunch of sugars in it. AN Bud Candy has the exact same effect. They might just be overdoing it. Another option is using small amounts of sodium or potassium if you make your own as an alternative electrolyte to prevent that from happening.


So I usually flush with RO water prior to harvest and I definitely agree its not the best method for doing it. Hearing you recommend AGT-50 got me interested though, you’d just add it to the RO at a certain rate to make a flushing solution?


Yes, the minerals in AGT-50 keep osmotic pressure and raise brix. The fulvic acid makes the plant absorb excess fertilizer instead of just washing it out. I typically do it at 1ml/gallon for ~40-50 ppm minerals.


I use to flush w clf-100 I thought I was doing something right… But I also used nutes that had to chelate or whatever it’s called was a calcium base nute w no salts

Wish I had agt50 back then but only full power fukvic and humic acid product

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can anyone insights on the effect these various flushing methods might have on biomass that eventually gets extracted? specifically, with ethanol, end product distillate?
context: recently we’ve experienced a higher than normal occurrence of ‘char’-like material in our WFE still bodies, that tend to be specific to one farm’s material but not the next’s. these are very water-soluble compounds, in my past research the forum seems to agree they are sugars (i tend to remain objective and call them ‘water-soluble impurities’ until i have more direct evidence). we’ve been testing the various theories where we can (lower-than-normal proof ethanol, finer-than-normal grinding of biomass, etc)
my question is, is it possible that sugars added during these flushes, OR not removed because of NOT flushing (thus remaining in biomass in higher quantities), or somewhere in between, could lead to these higher than normal occurrences of water-soluble residues down the line? this is the other theory brought up by one of my operators, and is the one i can’t directly test, at least with our current equipment.
(i suppose we could buy a brix meter and test the biomass prior to extraction; again if anyone has insight to those possibilities i’d love to know)
cheers! this is a great thread, thank you all

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1ml/gallon is pretty damn nice application rate for my wallet. Not to go off on a tangent but you mentioned raising brix. Got any data on percentage increase when using AGT-50 vs not? I know theres alot of variables that go into brix level that make it kind of hard to draw direct comparisons but id still be curious.

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I could see how a sugar based (sucrose, dextrose, fructose) could overexert osmotic pressure, to make plants “swell” with water weight before harvest. They would also remain after chop.

@Gregory we are testing all the time. We have a European sugar beet study we just finished that shows raised brix.