How much water do I use to flush?

Hello, I have an obama kush growing outside in a 35 gallon smart pot. I’m planning to harvest on the 19th and plan on flushing the plant next Friday, one week before I harvest. I don’t have a PPM meter so I have two questions. First is how much water do I use to flush? Is it really one gallon per gallon of growing material? That is a HELL of a lot of water. The second question I have is is there any way to know without the PPM when it’s good to go? I’ve heard just go until the water runs clear. Thank you.

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No, it’s actually three gallons per gallon. So if you have a 5 gallon pot, you’re going to flush with 15 gallons of water. That should do it if you don’t have a PPM meter.


@raustin is right, 3:1 is the standard in soil that most people go by, however i highly doubt is gonna take you 105 gallons to flush.

I would buy the ppm meter, you can get some as cheap as 10 dollars. As far as the flush, unless you just wanna spend 100+ dollars on distilled, which i wouldn’t, but that is me, i would just take the garden hose and run it through the soil for ten minutes and follow that up with 5-10 gallons of distilled.


Yes, that’s a perfect solution. Personally, I never use distilled water for a flush, just straight from the tap.


Awesome, that is great insight. Thank you.

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I do the same. I dump about a gallon of tap water into the pot, let it sit for 10 minutes, then turn the hose on low enough so that the water doesn’t pour over the sides of the container. I let it run for 15-20 minutes. Occasionally turning off the water and letting the soil just sit, and then resuming the flow.
At the end I slowly pour 3-4 gallons of h2o pHd to 6.5 into the soil. At this point pH probably isn’t an issue but I do it anyway.

It’s nice and easy doing a flush outside. The water can just drain off. Flushing my indoor plants involves a lot of wet vac use and dumping outside.


I am just now starting to grow. So I have 6 plants in 10 gallon smart bags and they are around 8 weeks old. I havent ever flushed them and I bought some Sledgehammer. So should I flush with 10-15 gallons of just water then hit them with the sledge and then continue to flush? Or add it at the beginning and then flush?

First let me start out by saying; I’m a first time grower and I’m sure having my share of screw ups. Lately I have been having an issue with nutrient lockout. I had given what you suggested some thought before reading this, but what stopped me was the water here. The water is chlorinated and has a ph of around 8 point something. Another words the ph is high. So, what you’re saying is if I put the hoes to my 6 ladies and let the water run for about 10 minutes and then follow up with 5-10 gallons of distilled water that should do the trick? How about following up with 5-10 gallons of 6.5 ph water will that work as well?

Hi I’m a new guy. I grew some pot a long time ago but that was way before all this hybrid stuff. The seeds I used came from Mexican brick weed. Now that shit was easy to grow, not as good as the hybrid pot of today but it was really easy to grow. Just about all you had to do was dump the seeds in a pot and that shit practically grew itself and it wasn’t bad either, got a good buzz off of it. Anyway, I’m having an issue with nutrient lockout. I read what you said about “dumping about a gallon of tap water onto your pot and letting it sit for 10 minutes” Then you write; “then turn the hose on low enough so that the water doesn’t pour over the sides of the container.” This is where I get a little confused. Is this water the same as the tap water only it’s hooked up to the water hoes? Or is this hoes hooked up to a pump that pumps ph 6.5 water through it? Couldn’t I just use the hoes and pour about a gallon of regular water into the soil and let it sit for 10 minutes? I’m not trying to be a wise guy or anything, I’m just a little confused. Couldn’t I let the water run until it runs clear? Or is the 10-15 minutes just to be sure all the crap has been rinsed away? Then you go on to say; “At this point pH probably isn’t an issue but I do it anyway.” Well, here where I live the ph of the water that comes out of the tap is around 8.7 or 9. That’s freakin’ high. Anyway, mainly what I’d like to know is; does the water that comes out of the hoes is that regular water or is it special ph 6.5 water? Says here that this entry was written about 11 months ago. I hope you’re still around and hopefully you’ll un-confuse my mind. Thanks Constipation

I can see where it’s confusing.

This was forever ago, but I was referring to the flush 10-14 days before harvesting. Not one early or mid grow to fix issues.

My municipal water comes out at pH 6.7-7.3 (no idea why it fluctuates). It DOES contain chlorine. I would use the hose water to slowly leach all excess salts and nutes from the soil, and then the properly pH’d and chlorine free water to (hopefully) leach the chlorine I may have introduced as well as fix the soil’s pH in place.

I said at that point pH wasn’t an issue, because the grow was done and nutrient uptake was no longer essential.

Well I feel like I have no other alternative other than to try what’s been outlined here. It’s either that or change out the soil. If you have any other thoughts please let me know.