Why do I have to keep adding pH down during flower?

rosecitypapa

rosecitypapa

Active Member
What's the metabolic process that keeps raising my rez water's pH? It's like this for the first couple of days after a changeout to a fresh rez.
 
J

Juicy Fruit

Active Member
1)pH fluctuates in smaller reses faster 2)Bacteria in the water cause it to change rapidly.

My suggestion is 50% H2o2 @ 1ml/gal per week should help stabilize and sterilize your rez.
 
taipanspunk

taipanspunk

Active Member
...it's not just bacteria, it's any organic matters forming in your water (ex. algae, mould, fungus, etc..)


FYI: I used to leave my water pump alone when I clean my containers and hydroton... slowly I noticed I had to watch my pH more and more frequent... it was until I notice a slimey coat forming around my water pump - once cleaned it it was way back to normal... (not saying this is your case)
 
rosecitypapa

rosecitypapa

Active Member
What if it's a sterile environment, does that mean pH will not rise? Does that also mean that there is nothing that the plant does metabolically that can cause a pH rise?

What if on the other hand, I was experiencing a pH drop?
 
rosecitypapa

rosecitypapa

Active Member
After the initial ph rise and subsequent additions of ph down, some stuff gets precipitated out of solution and rests at the bottom of my rez. Is this just the outcome of chemical nutrients interacting with each other? My ph stays stable after that occurs.
 
woodsmaneh!

woodsmaneh!

Well-Known Member
It always takes a day or 2 to have your ph stabilize after a change. There are lots of things that effect the ph. The best way to manage ph is to pick a spread your comfortable with and keep it between the ditches. Don't try to correct every time it moves a few points. The stuff you see on the bottom is fallout from what ever your adding. This is not a good thing, you need to find out what is causing it.

So for me growing in RDWC my ph is 5.4 to 6.5 as long as it's between that numbers it's all good.
 
meetjoeblow

meetjoeblow

Well-Known Member
it could be the quality of the water. when i started my dwc my ph use to raise almost hourly. because i was just sitting the water out to let the chlorine evaporate out of it. once i began to filter the water. a few hour turned into a few days before my ph fluctuated noticably ( please excuse my spelling ) . the next solution i came up with out of desperation. i was correcting my ph so much that i had ran out of ph down. me being 200 miles from the nearest hydro store, i had to find a quick alternative. i bought some hottube ph from the lowes down the street (sodium bisulfate to be exact) and dude i really havent had to ph since. i check it every week but its always the same. as long as i filter the water i can pretty much add the nutes directly into the system without worrying. and i checked forum after forum to see if it would be harmful but ive found a lot of people use it and they say no. the girls are doing great

View attachment 1461282
View attachment 1461281

this is just 4 plants and my hand stayed in the same spot during both pics
 
Serapis

Serapis

Well-Known Member
Here is the deal, your plant is going to adjust PH depending on the nutrients it needs. It's been my experience that in flower, the plants always tend to PH up and I allow them to. The reason being, in flowering the plant needs more Phosphorous and magnesium. Those nutrients are on the higher side of the PH scale. This is also around the time I start to see signs of Ca deficiencies, which is on the lower end of the PH scale. (Hydroponics) I have not had this issue growing with soil, which has different PH nutrient levels.

View attachment 1461299
 
rosecitypapa

rosecitypapa

Active Member
Serapis said:
Here is the deal, your plant is going to adjust PH depending on the nutrients it needs. It's been my experience that in flower, the plants always tend to PH up and I allow them to. The reason being, in flowering the plant needs more Phosphorous and magnesium. Those nutrients are on the higher side of the PH scale. This is also around the time I start to see signs of Ca deficiencies, which is on the lower end of the PH scale. (Hydroponics) I have not had this issue growing with soil, which has different PH nutrient levels.


View attachment 1461299
Click to expand...

Are you saying that the plant causes a pH rise in the root zone is for the purpose of making more of the elements that it needs accessible? In other words, if you were in a recirculating hydro setup, you would allow the pH to drift within a range. Have you personally tested if this is more effective than keeping a consistent pH of 5.8? What is the range you let it drift?
 
Serapis

Serapis

Well-Known Member
rosecitypapa said:
Are you saying that the plant causes a pH rise in the root zone is for the purpose of making more of the elements that it needs accessible? In other words, if you were in a recirculating hydro setup, you would allow the pH to drift within a range. Have you personally tested if this is more effective than keeping a consistent pH of 5.8? What is the range you let it drift?
Click to expand...
I let my Hydro units drift from 5.5 - 6.5. I do not adjust the PH if it is in this range, and most of the time it is. It does tend to go up naturally in late flowering, however when I adjust the nutrients, it comes back down.

squarepush3r said:
The roots absorb things out of the solution, and replace them with different things. So, for example a plant may take up (absorb) a nitrogen, and put back something in its place. The thing it puts back, can change the pH either up or down.

http://scienceinhydroponics.com/2010/06/understanding-ph-in-hydroponics-part-no-1.html

In short, if your PH is going up, you do not have enough nitrogen in your solution.
Click to expand...
That was a great read, but the author did not come to that conclusion, he was using Nitrogen as an example. That is one of the reasons PH fluctuates, not the only one. Check out chapter two of his article....
 
Serapis

Serapis

Well-Known Member
"However most growers tend to believe that the pH level of their nutrient solution is the pH level that plants have around their roots, something which is actually not correct in the sense that plants have evolved local pH adaptation mechanisms to survive to changes in soil pH. When you measure the pH of your nutrient solution you are measuring the pH of the “bulk” while the pH of the actual root-zone of your plants might be within the ideal zone for nutrient absoprtion. Therefore growers usually underestimate the actual capacity of their plants to correct pH and spend an enormous amount of time tinkering with pH to make it “ideal”."

Chapter 2 of above mentioned article. Like I said, let the plant drift and do not keep trying to bring the PH to a specific reading. The plant has the ability to adjust the PH depending on what it needs. Of course if your PH is too far outside the acceptable 5.5 - 7.0 range, the plant will not be able to make corrections due to large inbalances and lock out.

http://scienceinhydroponics.com/2010/06/understanding-ph-in-hydroponics-part-no-2.html
 
PetFlora

PetFlora

Well-Known Member
Approximately 3 week into flower the runoff pH will shoot up several points and ppms will jump well above ideal. The best thing to do is to monitor the runoff and when you notice the swing start D2W, as the runoff has the potential to toxify your nutes. If you use HPA, you don't use that much nutes to worry about the cost of D2W. hth
 
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