New Grower ph:the bane of my existence

[turtle360]

Check this out from another source:

In low light ( overcast days or indoor growing environments) plants take up more potassium and phosphorous from the nutrient solution so the acidity increases (pH drops). In strong intense light (clear sunny days) plants take up more nitrogen from the nutrient solution so the acidity decreases (pH rises).

Is there reason to believe the ph under 1000W MH is higher than the ph under lower powered cfls?

 

[Chester]

I don't know which I understand less women or ph ... :Sharing One:

 

[kato13]

That's a good thought turtle
Was thinking this myself the other night.
Would be good to hear peoples theory about this :Ohmmm.......:

 

[gone1]

I dont think so the pKs values of these molecules are so little they shouldnt make a big impact and there are a lot of buffers in the nutrient solution.
More likely the higher output of the HPS would cause more nutrient uptake and therefore change the pH faster. Usually the pH-value rises over time.

 

[turtle360]

I dont think so the pKs values of these molecules are so little they shouldnt make a big impact and there are a lot of buffers in the nutrient solution.
More likely the higher output of the HPS would cause more nutrient uptake and therefore change the pH faster. Usually the pH-value rises over time.

Wow. How you know that, pks values vs buffers? What I see about ph factors there seems to be a balance for every counter balance. Check it out, same source:

The ratio in uptake of anions (negatively charged nutrients) and cations (positively charged nutrients) by plants may cause substantial shifts in pH. In general, an excess of cation over anion leads to a decrease in pH, whereas an excess of anion over cation uptake leads to an increase in pH. As nitrogen (an element required in large quantities for healthy plant growth) may be supplied either as a cation (ammonium – NH4+) or an anion (nitrate – NO3), the ratio of these two forms of nitrogen in the nutrient solution can have large effects on both the rate and direction of pH changes with time. This shift in pH can be surprisingly fast. Daylight photosynthesis produces hydrogen ions which can cause the nutrient acidity to increase (lowering the pH). At dusk photosynthesis stops and the plants increase their rate of respiration and this coupled with the respiration of micro organisms and the decomposition of organic matter uses up the hydrogen ions so the acidity of the solution tends to decrease ( pH rises )
In low light ( overcast days or indoor growing environments) plants take up more potassium and phosphorous from the nutrient solution so the acidity increases (pH drops). In strong intense light (clear sunny days) plants take up more nitrogen from the nutrient solution so the acidity decreases (pH rises). pH can be controlled in two ways.

Daylight photosynthesis causes ph to drop. But under stronger light it rises. Right.

You say:Usually the pH-value rises over time. You mean ph increases over time? Or maybe it swings over time in cycles or tends to stubbornly stay low.

Don't bother. I'll try to hash out something coherent and be back when I figure it out (might be a while) Meantime for the hard stuff:

http://www.torontosnumber1datedoctor.com/NEWSLETTER ARTICLES/mystery.html

 

[gone1]

The part about the hydrogen ion happens in the leaves not in the roots. Cool article, is it about soil or hydro?
I think (could be totaly wrong here) that the pH shift alters over the lifecycle of the plants, pH rises in the veg. and decreases in bloom because of the different need for nutrients.
I just dont think that the difference in uptake of nitrogen, potassium and phosphorous under different lightsources would be that distinct to be noticed.
Since the pKs values of these ions are just soo little.
-1,47 for NO3- (about the some of H2O)

Edit: Okay i found your source, sounds like you could be right about that. Now im really interested if the difference of (for example hps/cfl) would be big enough to really have an impact.
Did anybody experienced such a coherence?

 

[daddyfatsax09]

How do you guys get your run off pH...I have airports if that matters any

 

[Trapper]

To be honest, it's worth the 50 or 60 bucks to get an Accurate 8 soil pH meter. Better data than the run-off method IMHO.

Plus the probe can give you readings from the top or the bottom of the pots which allows you to identify salt/nute build-ups
in the bottom of the pot (more acidic numbers)

 

[pop22]

Check this out from another source:

In low light ( overcast days or indoor growing environments) plants take up more potassium and phosphorous from the nutrient solution so the acidity increases (pH drops). In strong intense light (clear sunny days) plants take up more nitrogen from the nutrient solution so the acidity decreases (pH rises).

Is there reason to believe the ph under 1000W MH is higher than the ph under lower powered cfls?

PH rises and falls constantly, and is influenced by many factors. However, unless something is wrong to begin with, I doubt the changes will push the ph into a state thats too low or high. Nutrient availability can actually be enhanced by a variation within the availability window. And I doubt plants selectively absorb one nutrient in favor of another, just the ratio changes as the plants needs vary. PH issues in hydro are mostly caused by the water you use, and, or, the nutrients themselves. Poorly buffered nutrients will be sure to cause problems. And tap water, whether processed city water or even well water can wreak havoc with hydro and soil. I learned this first hand. took me months to pinpoint my water as the culprit that killed dozens of plants on me.
As to growlights affecting ph, I'm sure the higher powered ones may have some small affect, but there are so many variables I'd want to see a scientific study that accounted for them. I guess my point is, I'd worry more about your water and nutes than any light you use.

 

[Chester]

How do you guys get your run off pH...I have airports if that matters any

I set each one of mine in a plastic storage tote for watering once I pull them out of the grow space ... makes them slide around on the floor easier and catches the run off for testing or reuse on house plants ...
:tiphat: