question ph

[natoufly]

Hello everyone,

I currently have an aquarium in which there is a stump of chestnut collected in nature.

the water in this aquarium is black, you can't see more than a few centimetres, and the ph is 5 with 30 ppm.

there's just one big java fern.

three other aquariums set up at the same time (1 month) with the same substrate, but with aquarium roots, and the ph falls sharply below 7.3, with a low ppm too.

I can easily imagine the substances released by the chestnut stump.

Could you explain me ?

 

[MacZ]

What is the ppm? TDS?

If the KH is below 2°, drip tests and test strips for pH do not work anymore, if the EC is under 100µS/cm, a pH meter will not work either.

So tell us something about the way you measured the readings, what source water you use, and of course the numbers.

Maybe also a picture of each tank.

 

[MacZ]

To clarify: No two tanks will behave biochemically exactly the same, even if they are set up identically and run with the same water. Even if you can provide necessary information all explanations will be not much more than educated guesses and it is possible we won't find an explanation model that fits at all.

So just to make sure we don't overlook any factors, we will need:
- readings for KH and pH (essential), GH and EC or TDS (to rule out mistakes) for your source water and your tanks
- your measuring methods
- pictures of the tanks
- your waterchange regimen (frequency and volumes)

 

[Ben Rhau]

If his ppm is 30, it matters little whether it is GH or KH. The water is soft. Chestnut bark is acidic, so I think that's the reason.

Did you make sure that the chestnut stump has been dead for some time (completely dry)? You want to ensure there are no sugars from a recently living plant decaying in your tank.

 

[MacZ]

If his ppm is 30, it matters little whether it is GH or KH. The water is soft.

Well, if it's just KH, that still means 2°KH and I doubt that with botanicals alone it is possible to bring it down to a pH of 5.

If it's TDS or GH it is more likely. Without clarification I won't start speculating.

 

[natoufly]

Hello,



here is a photo of the aquariums they are all 60*30*30cm
placed lengthwise.
for any water change 100% osmosed water, 5l per week.
I do my pH tests with an electronic device, but the result is the same with the drop tests.

aquarium 1

pH = 7,5
kh = 2
uS/cm = 108
no2 = 0
no3 = 0

Aquarium 2

PH = 5,5
kh = 1
no2 = 0
no3 = 0

the strain is not of solid composition like aquarium roots, it must degrade rapidly and release a lot of tannin and humic acid into the water

Aquarium 3

PH = 7,25
us/cm = 192
KH = 3
N°2 = 0
N°3 = 0

 

[MacZ]

Looking at these tanks, seeing the numbers.. it all adds up between pH and KH. The higher the KH the lower pH, counting in accuracy. There is aldo the appropriate amount of botanicals to warrant each reading as well. Nothing unexpected to me.

 

[natoufly]

for my aquarium 2 the photo shows nothing because even with your eyes you can't see anything
are the ph measurements realistic?
to acidify water you need a large quantity of plant humus, and a low kh?
do you think the quantity and frequency of water changes are correct?

if I want to keep lowering the ph in both aquariums, it's only with time that this will happen and the gradual accumulation of organic matter?

why not use green plant compost without fertilizer instead of sand or mixed ?
a few years ago, i had a paludarium, and the soil in the aquatic part was made of green plant compost without fertilizer. i had Hyphessobrycon amandae that reproduced permanently in it. I've never tested the ph .

sorry if my questions are dumb

 

[MacZ]

are the ph measurements realistic?

Yes, but always remember there is a +/- 0.5 margin on the accuracy.

to acidify water you need a large quantity of plant humus, and a low kh?

Kinda, but you don't use humus but botanicals. Or do you mean peat? It's important to take your time with with the botanicals and for those to efgectively work the KH has to be basically below measuring threshold. EC below 50microS is what you're aiming for. Since you can still measure KH I suppose the wood was watered with tapwater and the sand washed with it? That means there will be KH leaching for some time from the material.

why not use green plant compost without fertilizer instead of sand or mixed ?

Because it contains tons of nutrients and you want to prevent that because we want humic substances in the water, not nitrogen compounds. Blackwater (or the approximation we can achieve i aquariums) is low in nutrients and basically anything.

Also... I see rocks in at least one picture. Hope it's not a limestone.

 

[natoufly]

Or do you mean peat?

no, not peat, I'm talking about the degradation of leaves, wood ...

Also... I see rocks in at least one picture. Hope it's not a limestone.

no, it's a granitic rock

if tank 2 has a very low ph, the strain has released a lot of humic acid, fulvic acid,
tannic acid?

how can i lower the ph in the other two tanks? maybe i need to lower the kh with more water changes?
by continuing to add organic matter?

(sorry if this isn't always clear, my English isn't very good)

 

[MacZ]

how can i lower the ph in the other two tanks? maybe i need to lower the kh with more water changes?
by continuing to add organic matter?

Exactly. Lower KH and keep adding leaf litter steadily. And be patient. It takes time.

(Sorry if this isn't always clear, my English isn't very good)

No problem, half of us here on the forum are not native english speakers either. What's your first language? Maybe we got somebody who can help you out.