Realize something about PH

[pimen]

So...
I start my pond water with RO water with pH 5.5-6
after several months, I notice my black taro growing slower and smaller
But still grow!
Then I bought pH meter n test it, n its 8.6
And It always stable up to 8.5-9
I don't know the cause of it
my pennywort grow quite well
Its crazy to think black taro n pennywort can grow in alkaline pH water as long as I know plant do well in slightly acidic pH 6.5-7
I just think their growth is not optimal
Is that true alkaline /high pH can blocked them to absorb nutrient optimally ?
I try several times change the whole pond water with my tap water (pH 5.5)
The pH drop to around 6
And after just a night, the next morning the pH came back to 7.5 n slowly become up to 8 again..
I dont know why my ph is always raise all the time
I read somewhere, if nitrification is already established, the water always goin to acidic condition..
Very very confusing about this f pond
Really hard to just lowering the ph

 

[Lisak1]

@pimen - your post is a bit hard to decipher, but I will say this: chasing pH in a pond is nearly impossible.

 

[pimen]

@Lisak1 I'm sorry, English isnt my mother tounge language
But the point is.... I dont why..., The ph level in my pond somehow always stable at 8.5/9..
Even if I do 100 % complete water change
The water down to 6 immediately then rising to 8 again in few hours later
So if chasing pH is nearly impossible....
Should I let it go just the way it is ?
I'm tired....
Once I questioned about the capability of bog plant to absorb nutrient in the pond
And now the pH water always raises
I'm done...... I don't give a sh*t anymore

 

[cas]

Hi @pimen . Here are some notes I have on pH.

• What causes PH to drop:
  • At nighttime the plants and algae use oxygen and produce carbon dioxide which causes the PH to drop if KH and water circulation are not sufficient.
  • Fish breathing will use oxygen and create carbon dioxide which will lower PH.
  • When the bio-filter is actively converting ammonia to nitrites it will lower the PH. When we feed our fish, the wastes create ammonia and the biofiltration process of ammonia conversion consumes alkalinity by producing acid. So unless there is a constant addition to the pond of some form of alkalinity (baking soda), the acid produced from feeding the fish will eventually consume the available alkalinity to give pH crash and loss of the biofiltration function.
  • Things that add tannins to your water can lower PH. When tannins are added, your water will have a brown or amber color. Tannins also soften the water (lower GH). Common sources for tannins are driftwood, oak leaves, peat, and formulations of black water extract.
  • Dissolved organics or sulfur compounds can lower the PH (water becomes more acidic) (lower pH)
  • Acid rain can cause a PH crash if the PH is already low and KH is low.
• What causes PH to rise:
  • During the day when the plants photosynthesize, they use carbon dioxide (CO2) to produce oxygen and this will raise the PH. If there is a lot of plants (including algae), this may be a substantial increase.
  • Installing an air diffuser (aerator) in the water will help dissipate the CO2 out of the water, which can increase your pH. Less CO2 = higher PH, generally.
  • Water with a high concentration of carbonates or salts of calcium or magnesium tends toward the basic (alkaline) (higher pH).

 

[MitchM]

I'll just add to Lisa and cas's posts.
In order to maintain a stable PH, you need to manage the KH and GH values as well.

 

[Lisak1]

I guess I'm still a little confused @pimen why it has you so frustrated? Why are you trying so hard to keep the pH down? Are you concerned about the affect on your fish or plants?

 

[pimen]

The problem solved
I added too powerful aerator in my pond
And yes aeration will make ur pH drastically high! Thanks @cas, so I remove it immediately,
@Lisak1 yes... I think the effect to the plant growth .....
Right now, I just use the water drop from my bog section to my pond to add oxygen in the system, I think that's enough,
Before this...., I only thinking about adding oxygen as much as possible to make aerobics bacteria grow n make nitrate, or give oxygen to the roots to make the plant grow better, based on this experience.., I realize that everything is must under proportion, the oxygen, pH etc....
Then now... my black taro and pennywort are growing normal and getting better n better cos the pH always stable at 6.8-7.2, it's like they absorb the nutrient optimally from my turtle n fish poops in the pond

 

[MitchM]

Measure your KH and GH and keep them within recommended levels to maintain a stable PH.
Strong aeration will not cause a problem, but it will reveal an existing problem.