pH Stabilizing

[HookedOnFish_MI]

Starting today, I am going to begin cutting my tap water with distilled water in each water change in an effort to get and keep my pH lower in my 15 gallon tank (by reducing KH). After about a week of every other day water changes, how long will it take for the pH to stabilize and get an accurate/final reading? There has already been magnolia leaves in the tank, and I am adding a couple nice size pieces of mopani wood today as well. I also have alder cones on hand if needed. I also know I will have to cut my tap water with every water change moving forward.
pH - 7.5
KH - about 3.18 degrees

Regular pH test:


High Range pH test:

 

[MacZ]

After about a week of every other day water changes, how long will it take for the pH to stabilize and get an accurate/final reading?

3-4 weeks until you see a clear change. And after KH has reached below 1-2° the pH will go down by 0.2 a month until it stabilises around 6.0-6.2.
Can't say how much the wood will impact, as you can never exactly predict the numbers with natural products. All numbers I give are approximations based on experiences.

 

[HookedOnFish_MI]

3-4 weeks until you see a clear change. And after KH has reached below 1-2° the pH will go down by 0.2 a month until it stabilises around 6.0-6.2.
Can't say how much the wood will impact, as you can never exactly predict the numbers with natural products. All numbers I give are approximations based on experiences.

Thank you for the information. It’s seems crazy to me that it will take 6 months for my pH to get to that point, based on your experience.

 

[MacZ]

Took mine that long as well. Patience is the hobbyist's best characteristic.

 

[dw1305]

Hi all,

how long will it take for the pH to stabilize and get an accurate/final reading?

It may not stabilise, as the water becomes softer you may find that the pH will fluctuate more, particularly if it is a planted tank.

cheers Darrel

 

[MacZ]

Hi all,

It may not stabilise, as the water becomes softer you may find that the pH will fluctuate more, particularly if it is a planted tank.

cheers Darrel

Though the daily fluctuation due to plant metabolism is also within a small margin and no danger to the fish. We're talking significantly less than 1.0 points pH.
Generally yes, a fluctuation of +/- 0.2 around a midpoint is to be expected. But that midpoint will go down so slowly it is in effect still stable. Guess the definition of stable with pH is never a rock-solid value that doesn't move at all, but a fluctuation within a small range.

 

[dw1305]

Hi all,

Though the daily fluctuation due to plant metabolism is also within a small margin and no danger to the fish. We're talking significantly less than 1.0 points pH.

I don't worry about pH changes, where they don't involve <"large changes in ionic water chemistry">.

Once you know that aquascapers, who inject CO2, aim for a 1 unit pH drop (~30 ppm CO2) and that each day their tanks drop a pH unit with CO2 on and then rise another pH unit when the gas goes off and that this doesn't damage the fish (although there may be long term sub-lethal effects) you know that it isn't pH change, as such, which is an issue.

In the case of added CO2 you've changed the CO2 ~ carbonate equilibrium pH value, but you also get similar effects in soft vegetated water during photosynthesis. Even really heavily carbonate buffered water, like the sea or Lake Tanganyika, shows a diurnal (diel) pH change.

This is from Diana Walstad's <"The Ecology of Planted Aquariums">

....... Daily variations of the water parameters are rarely – if ever – taken into account. Data collected in a freshwater lake (Star Lake, VT) with a very low alkalinity showed a diurnal pH fluctuation beyond the imagination of most hobbyists. Thus, the pH at 10 am was measured at 5.7 (strongly acidic), 9.6 at noon (strongly alkaline), 8.3 at 2 pm (moderately alkaline) and finally, 6.4 at 4 pm (slightly / moderately acidic). Readings were taken at a 0.5M depth. The fluctuation observed was due to the low KH value of the water (something reported for the Amazon river, too) and the presence of large amounts of phytoplankton. Under the circumstance it is extremely difficult, if not impossible, to figure what is the “right” pH for any form of aquatic life collected in that lake and which tank could cope with this kind of fluctuation. The low – high points of the day differ by 4 pH points, which means that the concentration of H+ in the morning is 10.000 times higher than at noon, while this change takes place in just two hours. It goes without saying that this pH swing cannot be observed in an aquarium only because we cannot reproduce the amount of light which falls in the Lake. In any case, if somebody reported that a suitable pH for aquatic life collected in this lake should range daily from 5.7 – 9.6 most hobbyists would think it was a typo.........."

The reference she cites is: Allen, H.L. (1972) "Phytoplankton photosynthesis, micro-nutrient interaction and inorganic carbon availability in a soft water Vermont Lake" In Linkens GE (Ed) "Nutrients and eutrophication... " Symposium Amer. Soc. Liminol. Oceanogr. 1 pp 63-83

cheers Darrel

 

[HookedOnFish_MI]

Hi all,

I don't worry about pH changes, where they don't involve <"large changes in ionic water chemistry">.

Once you know that aquascapers, who inject CO2, aim for a 1 unit pH drop (~30 ppm CO2) and that each day their tanks drop a pH unit with CO2 on and then rise another pH unit when the gas goes off and that this doesn't damage the fish (although there may be long term sub-lethal effects) you know that it isn't pH change, as such, which is an issue.

In the case of added CO2 you've changed the CO2 ~ carbonate equilibrium pH value, but you also get similar effects in soft vegetated water during photosynthesis. Even really heavily carbonate buffered water, like the sea or Lake Tanganyika, shows a diurnal (diel) pH change.

This is from Diana Walstad's <"The Ecology of Planted Aquariums">

The reference she cites is: Allen, H.L. (1972) "Phytoplankton photosynthesis, micro-nutrient interaction and inorganic carbon availability in a soft water Vermont Lake" In Linkens GE (Ed) "Nutrients and eutrophication... " Symposium Amer. Soc. Liminol. Oceanogr. 1 pp 63-83

cheers Darrel

Thank you both for this information. Truly appreciated!

 

[MacZ]

I always forget how many people use CO2. The range, as noted in the quote of Mrs. Walstad is much smaller in a tank, especially as here the tanks in question are not equipped with CO2 injection.

Hi all,

I don't worry about pH changes, where they don't involve <"large changes in ionic water chemistry">.

Once you know that aquascapers, who inject CO2, aim for a 1 unit pH drop (~30 ppm CO2) and that each day their tanks drop a pH unit with CO2 on and then rise another pH unit when the gas goes off and that this doesn't damage the fish (although there may be long term sub-lethal effects) you know that it isn't pH change, as such, which is an issue.

In the case of added CO2 you've changed the CO2 ~ carbonate equilibrium pH value, but you also get similar effects in soft vegetated water during photosynthesis. Even really heavily carbonate buffered water, like the sea or Lake Tanganyika, shows a diurnal (diel) pH change.

This is from Diana Walstad's <"The Ecology of Planted Aquariums">

The reference she cites is: Allen, H.L. (1972) "Phytoplankton photosynthesis, micro-nutrient interaction and inorganic carbon availability in a soft water Vermont Lake" In Linkens GE (Ed) "Nutrients and eutrophication... " Symposium Amer. Soc. Liminol. Oceanogr. 1 pp 63-83

cheers Darrel