pH SwingS

[stressed]

Hi All,

Need some advice here, at the end of the photosynthesis period with CO2 injection, my pH reads about 6.6. Lights goes off for the night and next morning about 8hours later, with lights and CO2 still off, the pH reads 7.1

Are such swings acceptable? What is the acceptable swing for CO2/Light ON/OFF periods, or should the pH maintain with the appropraite KH?

I have read so far that pH is a function of KH or vice versa and that would determine how much CO2 to inject during light ON period.

please advice....[] []

[joe]

Wats your kH value? pH swing of +-0.1 to 0.2 is okay I believe.

[bclee]

It depends on the surface agitation and the temperature. It is normal due to CO2 equilibrating with the atmosphere after CO2 shutoff.

The pH rise can be pH 0.5 up to 1.0. There should not be any problem.

BC

[Allen_1971]

quite normal. In fact, most of us have ph swings like that in our tank. The only ones who don't are those who don't inject CO2, or have fancy gizmos like PH controllers.

[stressed]

thank you all for the response, actually my concern is such pH fluctuations maynot be healthy for fishes as pH swings may kill [] []

since all mentioned that such swings are acceptable, that is glad to hear... but on the other hand is there a limit to the pH swing that would be catastrophic?

i have yet to start measuring my KH, cant find a suitable test kit at a right price....any lobang from anyone ?

[joe]

i got a spare kh kit from AquaMedi wanna let go. $5 only. PM me if u're keen

[stressed]

wah lau, missed it...just went to NATURE to buy KH Test kit. thanks for your offer.

btw...anyone here recommends any other forms of measurements? PO4, NO3, etc....

[eric_thian]

How about CO2? I off the lights & CO2 11pm. Every morning I check CO2 test kit indicate low CO2 and PH test pen indicate higher PH level. Is it normal for CO2 also?

[stressed]

i would say low CO2 in the morning or after a long period without CO2 injection will be normal.

because no matter how bad your fish load, you CO2 level should never rise to levels compared to that of injecting CO2. Thats why during light on periods we inject CO2 for photosynthesis.

BTW is there a real need for CO2 test kit? Wouldnt the test for KH and pH be able to conclulde the CO2 concentration ?

[chua]

Actually with the PH and KH test kits, you will be able to work out the CO2 in ppm in your tank. Note that it is advisable to invest on PH test pen cause it is much more accurate with an accuracy of at least 0.2. Normal PH test kits can't give you such high accuracy which is crucial in the calculation.