Adjusting PH in tank

[woodlands]

I have recently bought a PH pen. The ph reading in my 2ft tank is 7.5. then i tested the kh and it reads 8 [:0] . my Co2 is 3bp.

how do i bring both ph and kh down to the ideal range? i understand that ideal can be ph6.8 while kh is kept at 4.

will adding commercial chemical that adjust ph harm the system?

[geoffrey]

I have recently bought a PH pen. The ph reading in my 2ft tank is 7.5. then i tested the kh and it reads 8 [:0] . my Co2 is 3bp.
First, is your new pH pen calibrated? Check that.

how do i bring both ph and kh down to the ideal range? i understand that ideal can be ph6.8 while kh is kept at 4.
pH comes down if you add more CO2. What did you add into your tank to get a KH of 8? Water change helps lower KH. Ideal level - it depends.

will adding commercial chemical that adjust ph harm the system?
Folks here rarely do it this way, they use their CO2 to get the level they want.



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[vinz]

Errr, no need chemicals. Just do a few water changes... the KH of our tap water range from about 0 to 3, so a few normal water changes will lower it.

BUT, you need to check what is causing the high KH if you have not dosing anything to raise it. Probably culprits are coral chips, unsuitable gravel, or rocks. If there is something in the tank raising KH, water changes will only lower it for a while.

The ideal is not necessarily 6.8pH and 4KH. pH-KH pairs allow you to gauge your CO2 levels. Your plants and fishes wouldn't be bothered too much if it's 6.8 or 7.5 pH. You just have to make sure the CO2 is good for your plants.

If you look at Chuck Gadd'schart, at 7.5pH and 8dKH, you're only getting between 6 to 9 ppm of CO2. The recommended is 20 to 30ppm. From the chart, you can actually get a comfortable pH of about 7 or 6.9 with 24 to 30ppm of CO2... so just increase your CO2 gradually over a few days until you get that pH. It's much easier now that you have a pH test pen.

So if you are somehow getting a constant KH supply without trying, a few big water changes will bring it down, and regular water changes will maintain it. You just have to figure out how often and how much you need to change.

Oh yes, if you think your CO2 levels are fine and plants have been growing well, double check the calibration of your test pen.

[woodlands]

yeap, the pen is caliberated to 7.

thanks for the quick response guys, who go check it out.

[hobbit6003]

Haha, talking about test kits, my old kH test kit showed me that my kH was only 3dH, so I increased my Co2 output to bring the pH down to 6.6. Yesterday, when I bought a new test kit, the same water showed me a kH of 6dH! With the pH at 6.6, this gives me a CO2 conc in excess of 45ppm!

Thank God most fishes can tolerate a higher CO2 conc., and I've only gotten some yamatos, SAEs and Ottos for now.

For the planted tank, the best way to bring down your pH is definitely your CO2 gas. It is beneficial to your plants at the same time.

Cheers,

Kenny

[hobbit6003]

Oh yes, just another poin to ponder upon:

The CO2 chart is a good gauge no doubt, whereby the CO2 conc can be derived from the kH-pH relationship when CO2 injection is deployed.

However, in a matured tank, or one with large amt of new driftwood leaching out organic acid, wouldn't the correlation of CO2 conc and kH-pH be altered. since organic acids would also influence the pH value? It may not be significant, but I'm just wondering if the accumulation of organic acids, if it is allowed (eg. infrequent water changes), may give us a false CO2 reading.

Please allow my indulgence in little thoughts, which may not be of any significance.

Cheers,

Kenny

[PeterGwee]

Yes, organic acids will affect the pH a little bit but not much in my opinion. Infrequent water changes? Why? Water changes are good for both critters and plants.

There will always be some errors in readings no doubt, which is why we recommend you error on the higher side for CO2...closer to 30ppm is good.

[hobbit6003]

Hi Peter,

What I mean is that some hobbyist do not change water frequently, and if allowed to accumulate, the organic acids may affect pH in the long run.

Yeah, most fishes can take a high CO2 conc., some studies even showed tha black mollies can take up to 800ppm! Wondering if that's a print error, haha!

Cheers,

Kenny

[vinz]

Kenny,

The answer to your question.