Ah ken, you want me to start the shooting gallery har ...

from 8.3 u buffered to 6 deg, then the measured pH is 8.4. 0.1 only mah, sounds so little.

From 6.9 u buffered the same amount (assuming u have digitally measured to the exact), the pH and kH measured 7.4 and 6 deg respectively. 0.5 only mah, also little.

You have just proven 1 important factor - pH is not directly proportional to kH. And also, a big question i hv in mind is what acid did you use to bring the pH down from your usual 8+ pH to 6.9 ? What make your water high pH ? how did the acid bring it down ? how much buffer did u really add to make 6 deg, same as before u add the acid ?

Why is there such a big different in pH when carbonate is added at different ph of water initially ?

0.1 might not be significant to you for the time being. Period.

Have fun!

hahahahaha doc, dun apologize. Just my shooting machine lost control. hahahaha. This level is discussed in a higher technical arena. There are a few others here quite well verse in all these. kekekeke .... silent readers only mah.

Ah Kenn, the important issue to address here is, how much SB powder is to be added to fresh water to attain the required buffering, given a certain amount of water. Although the pH in the tap water is quite different for different areas in Singapore, the buffering amount for same volume of water should be roughly the same.

Why would anyone bother what the PUB do to make the pH in water in my area high?

Why would anyone bother how much pH will rise per degree kH raised at isolated pH range like below 5 or above 10?

Why would anyone bother the mechanism behind how acid brings down pH? This is science. Acid brings down pH, Alkaline pulls it up. That's all I need to know.

0.1 or 0.5 to me is small value change. In the end, the maximum BS you can add into the water is to make it ideally at 5dkH also. So why bother how much more powder can make anymore difference?

No point drilling at bull's horn if all that's needed to be known is already known.

It's okay. Just an advice, dun limit yourself to a small confine space and only to understand what you think you see is correct and unimportant. Those tests you have conducted were only the tip of the iceberg, the mass below is a hugh one. A 0.1meter increase in the height of the iceberg is a few times larger where you do not see at all.

Good luck.

away from the discussion...

assuming that the tap water is of pH 7.5 and my unchanged-yet water has a lower pH of 6.0

can i just add in BS into unchanged-yet water slowly, over a period of time, until the pH reaches 7.5 with the fishes inside? (that's how it's done right?)

I'm not sure BS works the same way as those products that do 'PH Up'.

Why would you want to buffer your old water for? As mentioned before, pH buffering is to make sure the water will maintain longer at a certain stabilized pH. It's purpose is NOT to raise the pH of your water. This act is dangerous

Ok, assuming that you do that...

The most amount of SB that you can add to your water, is the amount that will bring the dkH of your water to max 7dkH. Anything more than that might not do good for your fishes. So for example, if your old water pH is already at 6 and you buffer the water to 5dkH. And assuming that 0.2 rise per dkH increased (for that pH range), the pH in your old water will stablize at 7pH (6 + 5x0.2pH rise = 6+1). This might spell danger, depending on the temperature of the old water. Please refer to this chart on the toxicity of ammonium at different pH at 25 degrees celcius. The graph will shift for other temperature. But you can see the trend that at lower pH, the ammonia in the form of ammonium will be harmless to your fishes. At 25 degree celcius, if you do this, your fish are lucky to survive if it happened that the ammonia level is at a level of 4ppm and below (refering to that chart)

Upon seeing your old water is already at pH6, you ought to change the water 100% to be safe. Then having buffer the new water, the 100% water will be maintained at pH7.9 (7.5 from tap + little more due to SB) for a long time (say, one week). Meaning to say, the water will maintain at maybe pH7.9 for a steady one week. That's the way you should buffer your aquarium. Don't worry about the small increase in the pH of your new water at this point of time.

Things to take note of:
- If you never have the habit of buffering your water and want to start now, then do a 100% water change and buffer the new water to 5dkH accordingly.
- Do not buffer old water as much as possible. Meaning, buffer only new water.
- Observe water change routine as strictly as possible. 100% ought to be done regularly too. For eg, you do 30% change every wed and 100% change every Sunday.
- So for that 30% change, you only buffer the new 30% water.

pH Buffering will STABILIZE your pH. The main usage of SB is NOT TO RAISE pH. I personnaly see the "increment of pH" due to buffering, as a "side-effect". But there's no worry for this because the increment is always very little.

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Take another example. Same setup. But your old water is already at pH7. so you add SB to the water. The pH of the water rises due of this "pH increment side-effect of SB" to say, 7.5pH. Read the chart again from the 4.0 ppm down. You'll reach an "orange" area. At this point of time, it spells danger to your fishes.

4 ppm of ammonium ions measured at pH of 6 does not equate to 4 ppm of ammonia ions at pH 7 if buffering is added. NH4+ and NH3(aq) is not the same !!!

It's just for comparison lah.

A mastro like you might find this comparison faulty. But my intention is to explain a not-so-easily-understood theory to a newbie.

There's no need for obscure findings/bombastic words to scare newbies away.

pH buffering is a must. Period.

Won't that subject your fish to extreme pH swing up. I thought (For the first time) it is better to raise the pH slowly of the old water over 2 days before the water change i.e. raise from 6.0 to 6.5 on day 1 and 6.5 to 7 on day 2 and on the third day change water and add buffer

The ammonium/ammonia is in the water.

So if you change 100%, a pH shock to the fish is better than ammonia poisoning, instant deaths like HB's past case.

For BB:
The optimum pH range for Nitrosomonas is between 7.8-8.0.
The optimum pH range for Nitrobacter is between 7.3-7.5

So at lower pH, I supposed your BB might be struggling. Or might already have collapsed. Ammonia/ammonium naturally is very high at this point.

I'm not too convinced that BB is not there at pH6. Arowana keepers maintain their water at that level as well. Although I have never encounted this situation, but I do think that pH shock is stressful especially 2pH jump.

I think 2 pH jump can kill.Thats 100 times difference in acidity / alkalinity.

I share the same sentiments,though my example is at the other end,marine tanks.
Their pH are always above 8,and BBs are thriving as well.

supzfier .. how are things?