End of flowering PH dropping

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Medigrow

Medigrow

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Hey everyone! :)

Another run, another issue with the ph dropping at the end of flowering.. Started week 8. PH was dropping down to 5.3.. I did a flush, refill using 150ppm solution and ph 5.8. I took time to look at the roots and everything is perfect, (white roots with a nice smell), no biofilm or whatsoever. I refill the topoff using the leftover, 1 day later, ppm was at 100, I added nutrients in the topoff to put it at 200, trying to raise the ppm a bit since it was getting used by the plants. Adjusted the topoff's ph at 6.8 and... System's ph is dropping again... now back to 5.3 and system is still at 100 ppm. I added only RO water to topoff, it is around 50-60ppm right now, ppm of the system isn't going up, nor the ph. Co2 is at atmosphere level. I cut it few days ago.

I had water temp set on 64 for last 2 weeks.. range from 63 to 65. I raised the temp from 1 F, just in case.

Anyone has any clue about this? I don't see any bacterial bloom, water temperature is fine, nut's strength is well, kinda low but not even getting absorbed by the plants. And yes, they are drinking.

RDWC system.

Is it time to flush? The trichomes are ~5-8% clear, 90% milky and leftover are turning amber.

Thank you!
 
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Medigrow

Medigrow

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150ppm is nothing, is that right? is this hydro, soil?

We're in the hydro thread but yeah, I will add to my topic :D

150 ppm is nothing but I have a good air input so I have to lower my ppm. Can't go higher than 450 else I see burned tips.
 
OldManRiver

OldManRiver

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No need, just wanted to understand. I am puzzled. My tap water alone is over 150ppm. Usually my nutes are running at 900-1100. What brand of nutes are you using?
 
Aqua Man

Aqua Man

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You don't have enough buffer to hold your ph stable.

Why are you flushing in hydro? It makes no sense? Flushing is only beneficial in soil to lower nutrient concentrations of the soil. In hydro just lower them. Nothing will pull excess nutrients from the plants if they have been over fed.

Plants still need nutrients to develop bud they just require a lot less at the end of flowering. Starving your plants is not going to help.

Feeding properly throughout the grow and not over feeding is the key. Robbing them of nutrients in the end won't really fix it.

Cutting back on nutrients makes sense but flushing in hydro makes no sense.

I'm sure people will disagree.
 
Aqua Man

Aqua Man

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We're in the hydro thread but yeah, I will add to my topic :D

150 ppm is nothing but I have a good air input so I have to lower my ppm. Can't go higher than 450 else I see burned tips.
What does air input have to do with it?
 
Medigrow

Medigrow

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You don't have enough buffer to hold your ph stable.

Why are you flushing in hydro? It makes no sense? Flushing is only beneficial in soil to lower nutrient concentrations of the soil. In hydro just lower them. Nothing will pull excess nutrients from the plants if they have been over fed.

Plants still need nutrients to develop bud they just require a lot less at the end of flowering. Starving your plants is not going to help.

Feeding properly throughout the grow and not over feeding is the key. Robbing them of nutrients in the end won't really fix it.

Cutting back on nutrients makes sense but flushing in hydro makes no sense.

I'm sure people will disagree.

My other system is running fine at 100 and 5.9, no ph drop... That's why I'm kinda confused.

As for the flush in hydro, you need one but only 2-3 days are "required".

And, in my veg room, ppm is at 120-130 and ph is raising...
 
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Aqua Man

Aqua Man

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My other system is running fine at 100 and 5.9, no ph drop... That's why I'm kinda confused.

As for the flush in hydro, you need one but only 2-3 days are "required".
Why is it needed?
The more air input, the less ppm you need. (Taken from Cultured solutions website)
News to me.... I don't buy it I cannot see any reason air would affect nutrient solution strength. But I'll see if I can't find their reasoning behind it.
 
Aqua Man

Aqua Man

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Can't find those claims. But if you add some cal mag to the water and then ph it should fix your ph issue.
 
Medigrow

Medigrow

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Why is it needed?

News to me.... I don't buy it I cannot see any reason air would affect nutrient solution strength. But I'll see if I can't find their reasoning behind it.

As there is more oxygen in the water, the nutrients are more accessible to the roots, so lower ppm is required.

And, I tried to follow the schedule... I'm burning them once I pass the 450ppm mark.


As for the calmag, I'm in the end of flowering, I won't add only ca/mg nutrients... I just raised the ppm solution, I will see how much it will be tomorrow... It should reach 180-200ppm, waiting for the topoff to drip =)

The starving point is a good point... I was wondering how much is "starving"...
 
Medigrow

Medigrow

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I don't know if I can past a link here but


"The increased availability of oxygen atoms also enhances the uptake of nutrients. Oxygen-deprived roots have no option but to substitute with other compounds and start producing ethylene, which causes cell damage and increases the chance of systemic disease."

 
Medigrow

Medigrow

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Why is it needed?

So in soil, you need to flush but not in hydro, can I understand your idea behind this claim? Everywhere they suggest to flush even in hydro... I could use the same pattern, in soil, if you don't overfeed, no need to flush because the plant only took what it needed and the leftover are still in the soil.
 
Aqua Man

Aqua Man

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As there is more oxygen in the water, the nutrients are more accessible to the roots, so lower ppm is required.

And, I tried to follow the schedule... I'm burning them once I pass the 450ppm mark.


As for the calmag, I'm in the end of flowering, I won't add only ca/mg nutrients... I just raised the ppm solution, I will see how much it will be tomorrow... It should reach 180-200ppm, waiting for the topoff to drip =)

The starving point is a good point... I was wondering how much is "starving"...
I see what you are getting at but let me kind of explain the science behind it. Often times companies twist things to suit there marketing needs.

DO is directly related to water temp and plants need it in order to carry out processes including nutrient uptake.

Now it only effects nutrient uptake when it is deficient. The plant will not increase nutrient uptake with DO levels beyond what it needs.

O2 is also a very hard gas to dissolve in water without increasing pressure. However as the level of DO drifts downward from equalibrium (as determined by water temp) the rate at which o2 or any gas lower than equalibrium will exchange is increased.

We only need to maintain adequate levels of DO and more does not increase nutrient uptake. You also cannot have anaerobic conditions in hydro because we have no medium to create it.

There are a ton of factors that increase nutrient uptake so going by manufacturer feed schedule is a bad practice and should be used as guidelines. Most often these schedules are made for plants growing under extremely optimal conditions and therefore are very rarely used in full doses. There is a crap ton to this but I will just leave it at that.
 
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Aqua Man

Aqua Man

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So in soil, you need to flush but not in hydro, can I understand your idea behind this claim? Everywhere they suggest to flush even in hydro... I could use the same pattern, in soil, if you don't overfeed, no need to flush because the plant only took what it needed and the leftover are still in the soil.
So in soil you can't just change the nutrient concentrations at will like hydro. So in soil they flush to lower the nutrient concentrations and in hydro all we need to do is lower them
 
Medigrow

Medigrow

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So in soil you can't just change the nutrient concentrations at will like hydro. So in soil they flush to lower the nutrient concentrations and in hydro all we need to do is lower them

Are you going RDWC?

Glad we can exchange without falling into insults! =) I'm loving it!

As for the DO, if it was a twisted thing from the company, they wouldn't say we need less ppm if we have a better air input because we can use less nutes, which is "bad" for them. My ladies drink 40-45 liters a day... I feel like training a sumo team! ahah
 
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