Flushing help please

Hi there. I am literally in the middle of flushing my plants. I am currently flushing a Bubba Kush.I am trying to correct a high soil tds/low pH (as I was advised to do on this awesome forum). I have flushed twice already. After the first flush ( it dropped from 1800ppm to 950ppm. So I flushed again and it only dropped to 750ppm. I have put 8g in total. My research has told me to keep flushing until 50ppm or close to. Can the plant handle this? Why such a dramatic change in numbers from the first flush compared 2nd? Any help would be appreciated as I am literally in the middle of this. Many thanks!

I’m not sure who advised you to flush all the nutrients out of your soil, it was bad advice, especially trying to flush down to 50ppm.

A fresh bag of soil will have a ppm of between 2000-5000 ppm. Those are the nutrients that are found in soil that allows soil growers to go for 6-8 weeks (or longer) before the need to feed the plants. This is why soil is often the first growing medium recommended to novice growers. Once the nutrients are gone you need to feed your plants for them to thrive.

Coco and peat based products have no nutrients and require feedings as soon as the seedling comes up. Growers experienced in feeding prefer being in complete control of what their plants receive.

You need to stop flushing and let the pots dry out a bit or you will damage the roots.
You need to invest in a nutrient line and begin feeding right away, once ppms in soil fall to approximately 1000 it calls for full strength feedings.

Was there something going on with the plants that had you concerned before you began flushing, or did you just misinterpret the information you read that convinced you to flush?

What are you trying to accomplish by flushing? Are you getting ready to harvest? How about a picture of the plant or plants?

Thanks for the response. Several of my plants are showing signs of nutrient deficiencies. I posted about them a few days ago. I pasted the thread below. I got the 50ppm info from an article on RQS when I was researching flushing. It said the following:

Flood the soil with as much fresh water as it can hold. Leave this for a few minutes to allow all of the nutrients to be picked up, the flood the soil again to flush it all away from the plant. If you are indoors using pots, notice the colour of the water that is draining from the bottom of the pot. It will be stained and look dirty. This is where a TDS (total dissolved solids) meter will come in handy. If you were to collect and measure the TDS of the “drained off” water, it would be around the measurement of 1300ppm, which is pretty high. It is important to keep flushing the plant until this number drops to a level of 50ppm, or at least until it is close to matching the TDS of the fresh water that you are using to flush with. The colour of the draining water will lighten up and appear to be cleaner. You want to get as much of the dissolved minerals away from the plant as you can

Hello! Working on my second grow, and I am hoping for guidance on soil pH. I have 5 plants of different strains going (2 photos and 3 autos) and I think they all seem to be showing different signs of nutrient deficiencies. Brown crispy edges on leaves of Bubba Kush Photo (midbloom). Red Stems on F’ing Incredible Photo (early bloom) and on Amnesia Auto (mid to late bloom). And poor Northern Lights Auto (mid-bloom): crunchy, orange and copper speckled leaves (I think it’s a calcium deficiency?). I use FF Happy Frog in 5g pots. feed GH Flora Series with CaliMagic at just above half the recommended dosage. I feed every other watering and I have been pHing to 6.3 (which I guess has been to low?) I try to get 15% to 20% runoff. And I measure the pH of it and it is really low, therefore affecting the plants ability to uptake the nutrients, right? If I’m going in at a pH of 6.3 I’m getting runoff readings as low as pH of 5.3, 5.1, 4.8 etc. I have been trying to research how to raise the pH of my soil but have found a lot of confusing information and lots of contradictory info! Looking for some guidance please! I am looking at adding Limestone dolomite (but is it to raise or lower pH?) to the top layer of soil and then raising the pH to almost 7 for feedings and watering. Would that help? Gonna hold on till I see what folks have to say. Many thanks for your time!

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](Soil pH problems! - #12 by blackthumbbetty)

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pedally

2d

photos would be a big help. Welcome to the board. Taking on 5 plants on the 2nd grow can be challenging.

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blackthumbbettyBergman’s Lab

2d

A good flush should help your plants. Then, start your input higher (say 6.8 max), since you know your pH drops out. Also, no need to feed every other watering with Happy Frog and those nutes. That combo will cause fast acidification of the medium.

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CMichGrower

2d

What kind of lights? Just curious.

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20h ago

Myfriendis410ILGM_Moderator

1d

How about some pictures in white light and fill this out? It will help a bunch to get a good diagnosis.

COPY/PASTE the below list into your forum post.

Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so; Or post
NA (non applicable)

  • What strain, Seed bank, or bag seed
  • Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF
  • Vessels: Pots, Grow beds, Buckets, Troths
  • PH of Water, Solution, runoff (if Applicable)
  • PPM/TDS or EC of nutrient solution if applicable
  • Indoor or Outdoor
  • Light system
  • Temps; Day, Night
  • Humidity; Day, Night
  • Ventilation system; Yes, No, Size
  • AC, Humidifier, De-humidifier,
  • Co2; Yes, No

Always try to upload a clear picture of any issues you may have to allow the community to assist you.

Add anything else you feel would help us give you a most informed answer should be included. Feel free to elaborate, but short and to the point questions and facts will help us help you in a more efficient manner :slight_smile:

Thanks!

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Cannamom

1d

Ok, thanks for the tips. Here we go.

As @pedally said in the comments 5 plants for a second grow could be challenging. But it just kinda happened and I’m not one to back down from a challenge, so here we are!

Before listing each plants info it should be noted that all 5 had a rough start. I thought I was set up pretty good and wasn’t sure why my plants weren’t doing much. They were, but very slowly. A couple didn’t even make it. And there were a couple that I thought weren’t going to make it so I planted a couple more lol. And I planted the GG4 about 5 weeks ago cause why the heck not? Well, it took me awhile to figure out that the wattage of your light may not be what is advertised and that I should be measuring what is actually being pulled out of the wall. I didn’t have nearly enough light. I adjusted everything so that both my auto tent and my photo tent had the right amount of light. That changed everything pretty dramatically and things were going pretty well for a while. But the photos vegged for quite awhile and they both started flowering on their own a few weeks after the lights were adjusted. As soon as I noticed this I switched them to 12/12. Autos are 18/6.

What strain, Seed bank, or bag seed

  • F’ing Incredible, Pacific Seed Bank (breeder: Norcal Farms)

Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF

  • soil, FF Happy Frog

Vessels: Pots, Grow beds, Buckets, Troths

Fabric Pots, 5g

PH of Water, Solution, runoff (if Applicable)

Latest readings: water: pH 6.3, runoff: pH 5.6

PPM/TDS or EC of nutrient solution if applicable

N/A (honestly just haven’t bitten this piece off yet)

Indoor or Outdoor

- Indoor

Light system

- 110W LED full sprectum white + 70W burple LED

Temps; Day, Night

- Day: 23C-24C

-Night: 21C-22C

Humidity; Day, Night

-Day 40-45

- Night 40-45

Ventilation system; Yes, No, Size

- Yes. 200CFM, 4” carbon filter

AC, Humidifier, De-humidifier,

-No

Co2; Yes, No

- No

What strain, Seed bank, or bag seed

- Bubba Kush 2.5, 34th Street Seed Company, Legal Breeder in Canada

Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF

- Soil, FF Happy Frog

Vessels: Pots, Grow beds, Buckets, Troths

- Fabric Pots, 5g

PH of Water, Solution, runoff (if Applicable)

- runoff pH5.5

PPM/TDS or EC of nutrient solution if applicable

- N/A

Indoor or Outdoor

- Indoor

Light system

- 110W LED full sprectum white + 70W burple LED

Temps; Day, Night

- Day: 23C-24C

-Night: 21C-22C

Humidity; Day, Night

-Day 40-45

- Night 40-45

Ventilation system; Yes, No, Size

- Yes. 200CFM, 4” Carbon Filter

AC, Humidifier, De-humidifier,

- NO

Co2; Yes, No

-NO

What strain, Seed bank, or bag seed

- Amnesia Auto, Canuk Seeds

Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF

- Soil, FFHF

Vessels: Pots, Grow beds, Buckets, Troths

- Fabric Pot, 5g

PH of Water, Solution, runoff (if Applicable)

- Last Reading: water pH: 6.3, runoff pH: 5.6

PPM/TDS or EC of nutrient solution if applicable

- N/A

Indoor or Outdoor

- Indoor

Light system

- Mars Hydro TS3000, set to 270W LED Full Spectrum White

Temps; Day, Night

- Day: 23C-24C, Night: 21C-22C

Humidity; Day, Night

- Day: Approx 50%, Night: Approx. 50%

Ventilation system; Yes, No, Size

- Yes. 800CFM, 8” Carbon filter

AC, Humidifier, De-humidifier

- Humidifier

Co2; Yes, No

What strain, Seed bank, or bag seed

- Northern Lights Auto, Canuk Seeds

Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF

- Soil, FFHF

Vessels: Pots, Grow beds, Buckets, Troths

- Fabric Pot, 5g

PH of Water, Solution, runoff (if Applicable)

- Last reading: water pH: 6.1, Runoff pH: 5.36

PPM/TDS or EC of nutrient solution if applicable

- N/A

Indoor or Outdoor

- Indoor

Light system

- Mars Hydro TS3000, set to 270W LED Full Spectrum White

Temps; Day, Night

- Day: 23C-24C, Night: 21C-22C

Humidity; Day, Night

Day: Approx 50%, Night: Approx. 50%

Ventilation system; Yes, No, Size

- Yes. 800CFM, 8” Carbon filter

AC, Humidifier, De-humidifier,

- Humidifier

Co2; Yes, No

- No

What strain, Seed bank, or bag seed

- Gorilla Glue # 4 Auto, Blimburn Seeds ( got a 3 pack of seeds and 2/3 didn’t even germinate – not sure how good these are)

Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF

- Soil, FFHF

Vessels: Pots, Grow beds, Buckets, Troths

- Fabric Pot, 5g

PH of Water, Solution, runoff (if Applicable)

- Last reading: water pH: 6.3, Runoff pH: 5.7

PPM/TDS or EC of nutrient solution if applicable

- N/A

Indoor or Outdoor

- Indoor

Light system

- Mars Hydro TS3000, set to 270W LED Full Spectrum White

Temps; Day, Night

- Day: 23C-24C, Night: 21C-22C

Well, there it all is. So many thanks to anyone who takes the time to go through this. :slight_smile:

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Cannamom

CMichGrower

1d

Hey! please see below!

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Cannamom

blackthumbbetty

1d

Hey thanks for the advice! I was prompted to give my info so I posted that. Would you still suggest the same thing?

1 Reply

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Cannamom

pedally

1d

Hi! I posted pics and details below! thanks!

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blackthumbbettyBergman’s Lab

Cannamom

23h

Yes, I’d still say it’s most likely your ec/tds and pH. In bloom, we want that pH to be about 6.7-6.8.

I still recommend a flush at about 6.6 followed immediately by a light bloom feed at about pH 6.8.

I don’t topdress, myself, but some lime with the non blooming girls would help with pH. The plants that are firmly into bloom won’t get as much benefit from the lime, since the lime is a slow release element.

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Cannamom

21h

OK, thanks so much for the response @blackthumbbetty . I will flush all of them at 6.6, followed by a light bloom feed at 6.8.
Should I wait for the plants that were more recently watered to dry out or should I go ahead and do them all as soon as possible?

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blackthumbbettyBergman’s Lab

20h

You’re in cloth pots, right? You can certainly flush & feed, now. Then, you probably won’t need to water for 5 days or more.

Here is all the info. Your input and advice is appreciated. Many thanks.

At this point in their life cycle there is no reason to take them all the way down to near distilled water levels. A flush should take you down in soil to under 2,000 ppm or so and in soilless 1,100 ppm is what I shoot for. That or simply water-only and monitor runoff until you reach the above value.

I do flush to low TDS numbers ahead of harvest as I’ve found the finished flower to be smoother.

There are also products like GH Flora Kleen and FF Sledgehammer as flushing agents.

2 Likes

Been growing in ff soil for a while now the first I noticed is you were feeding half strength nutes and gh series,you definitely have nute burn I usually start feeding nutes when runofff ppm drop bellow 800 and not before except for some cal mag,then start with half doses I would also recommend some Microbes to help those. Roots uptake nutes I like recharge it will also increase your ph of the soil and extend your plants ph range a bit and if you compare a soil grow to. A coco grow you are going to feel like your going slow but relax the soil breaks down nutes into a form the plant can uptake and is a process as where feeding hydro the nutrients are already. In a plant available form

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They’re flushing bc of pH issues.

I wasn’t aware you were flushing for high tds. I thought you were concerned about your pH. Your nutrient deficiencies are most likely from your low pH. Just get your pH under control with the flush, then give a light feed at the appropriate tds.

A flush requires up to 3x the amount of water as the size of your pots.

What is your pH? Why aren’t you measuring that? Your tds means nothing if your pH is down to 5.5 in soil.

I think you researched pre-harvest flushing. This is not what you’re doing. You’re flushing to fix a severe pH issue.

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hey @blackthumbbetty . Yes, I was obviously a bit confused. I have flushed 3 of my plants so far, but the pH isn’t really improving. That being said, I didn’t use 15g/plant of water. I am in 5g pots. I used 8g for Bubba Kush, 12g for GG4 auto, and 6g for Northern Lights Auto. I just put in what I thought each could handle… Didn’t realize I had to use so much water! Then I followed with a light feed, but 3/4 of it ran right thru. I put a gallon in each, wasn’t sure how much to put in. But the pHs are all still very low. Bubba Kush 5.2, GG4 5.1 and Northern Lights is 5.4. Oh man. what a disaster lol. Please kindly guide me. Many thanks.

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thanks for the good info!

yup, i get that know. Many thanks for the info!

No, you gotta flush til the numbers change. That’s the point. What pH are you using to flush?

I’d flush with 6.8 pH water til the run-off is to at least 6.3. Then immediately after, give a light feeding at pH 6.8.

Then, you probably won’t have to water/feed for 5-7 days.

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Flushing has saved many wayward grows. It seems terrible while you’re doing it, but with fabric pots and a good environment, that extra moisture won’t cause any lasting harm, I promise.

I’ll try to check back more often than usual to help guide you along.

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Ok, you got it. I’m on it. I was putting in at 6.6, put I will adjust to 6.8. And I will continue until the pH comes up.

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It does seems terrible, but I will trust you lol. Thanks for your help, will keep you posted!

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I assure you, I’ve done many pH flushes and have helped many with their own flushes. I really am not trying to kill your plants. :grinning:

If after 5 gallons at 6.8 there’s ZERO movement of pH in the run-off, you can try going in at 7.0. But, only do that as a last resort. Since 6.6 didn’t do it after 8 gallons, time to get serious.

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@blackthumbbetty lmao, I would hope not!

Welp, sure enough, i dropped my pH pen in a huge vat of water (after my husband cautioned me not to numerous times) and by the time I fished it out again it was pooched. Ordered another one, arriving tomorrow. I can’t believe it. Till then not much I can do. :roll_eyes:

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Once you’re sure growing is your thing, invest in a waterproof pH meter, like a Blue lab or an Apera.

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Hey @blackthumbbetty , hope you are keeping well. I ended up getting a Blue Lab (its my thing, I may not be good at it yet, but I will be. In time lol.) Life changing. Wayyy more accurate as well. I’ve been able to get my Northern Lights from a 5.4pH to a 6.2pH (after nutes 6.1pH). its still low tho right?
I am doing Fing Incredible rn. I have flushed with 15g in total (in 4.5g increments checking runoff pH for each). It went from 5.5pH to 6.0 and after the last 4.5g has only gotten to 6.1. Not sure if I should keep going, or feed (which will probs bring it down a bit?)?

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It’s still low, but a definite improvement. Great job! Flushing is a daunting task.

I’d go ahead and do another few gallons in at 6.8 or so. It should inch up to at least 6.3. Then, do a light feed with an appropriate tds/ec at that 6.8, checking run-off to get your base numbers to compare for next time.

Blue Lab is great! I love mine.

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