soilless - flush to adjust ph, remove old nutes

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Any advice on how to flush properly to remove excess nute buildup and adjust ph runoff, not before harvest, but more like once a month sort of thing, or when you want to rid your soil of all excess N and use straight P-K.

Here is what I currently do, let me know if I should change anything.

I get my water ready with 1/4 strength nutes, ppm of say 300 and ph'd to 6.0.
I begin to water and as it comes out the bottom I take samples, ppm starts out low at say 500, then after a few min of slow watering it spikes up to 1100ppm, ph is steady at about 6.7.

I continue to water until ppm reaches within approx 30% of whats going in, so I flush untill ppm comes out at say 400, but the ph is still at 6.7.

So then I add some extra bloom nutes to my water, ups to ppm to 400, but drops the ph to 4.5.

I continue to water with the ph meter underneath the pot, with the water trickling over the ph meter, I watch the runoffs ph slowly as I water and when it reaches 6.3 I stop watering, take one last sample to check ppm. Its sitting at 500.

So it starts off ph 6.7, 1100ppm, end result is ph 6.3 and ppm of 500.

Is this the proper way to remove excess nutes, and get your ph back to where you want it to be?

 

[pcduck]

Don't add nutes just water.
I believe the amount most use is 3x the size of the container.

I do not flush unless I make an error.

 

[Dr. Green Fang]

^ Everything that Duck said :aok:


I went back hydro so I didn't have to worry about my root zone so much. I've been having temp issues in my root zone, and there hasn't been too many things for me to fix it. Also, I wasn't sure about PH and had to do a run off test to check it. Granted my test came out fine and my issues were 100% temp related, it was still a pain to check it

And finally, like PCDuck said, it's about 3x the amount to flush it. If it's a 1 gal pot, that's 3 gal of water to properly flush the medium. Also, you need to get rid of the run off, and not let the medium soak that all back up.. which is a timeless and painful process. At least it was for me, there's loads of clever ways to sort that out and remove your run off decently easy.

Anyways, sorry for my ramble. 3x the water - throw the water away - keep root zone 65° + ... any lower than that and Nitrogen starts to lock out.

 

[The Hemp Goddess]

Flushing like this is not a good practice. Why are you dong it? I really do not understand the purpose behind what you are doing?

You do not really ever want NO nitrogen. Like the others, I only flush if I have a problem.

 

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This is the first time I have had testing equipment so I thought I would take this opportunity to try and learn something. There are some happy plants, and some not quite so happy plants. I figured the un-happy plants would appreciate the flush, and the happy plants were my test subjects to compare against the unhappy ones. Unfortunately there wasn't much difference between them, the ph was slightly higher in the unhappy plants.

They are 8 weeks old, should be ready to harvest in a week or two. They could use the flush anyways.

Plants were on average at a ph of 6.7.

 

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I am hoping to be able to monitor run off ppm for future grows, almost the same as is done in a hydroponic res. In theory you should be able to tell if you are over or under feeding your plant before it shows symptoms.

 

[Dr. Green Fang]

It just takes longer to adjust, but yes.. monitoring PH / PPM run off certainly help. Also, if your PH pen has a Temp spot on it (Bluelabs etc) you can see if that's an issue. I was putting my water in at 68° and the run off was 58°! I can imagine what the root zone was before the warm water!

Your plants look good to me.. a little "wear" has a way of showing near the end.

 

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These are the "happy" plants

 

[Dman1234]

I have never understood the point of checking run off, if i am putting the correct Ph in, my job is done, and i havent really experienced many PH related issues, jmo.

 

[Dr. Green Fang]

Pretty sure over time, like any medium, the PH will fluctuate due to many factors. With that said, I have yet to have a PH issue after checking my run off