What is an acceptable PH swing over 24hrs?

[ccwbank]

What is an acceptable PH swing over 24hrs for SPS?

I've been using aquaplanner pro to log my water tests and after charting the results for the last several days I'm seeing a low of 7.95 (7am) and a high of 8.20 (7pm) each day.

Thanks

 

[Frick]

That is quiet a bit for 12 hours. What is your alk and mg?

 

[talwen]

I asked this same question in the chemistry forum. Here is the link and graph I posted http://www.reefcentral.com/forums/showthread.php?t=2211332

 

[Mock]

Same as Talwen was told..... You not swinging that much. If you were swinging a whole point I would say yea you have problems but your only swinging like .25 over a 12 hour period... Thats not that much. Pretty typical.

 

[tmz]

FWIW mine swings from 8.1 to 8.35. Not a problem

 

[ccwbank]

That is quiet a bit for 12 hours. What is your alk and mg?

I don't have a mg tester but alk is 183 ppm on my Hanna checker.

 

[REEF SMAC]

FWIW mine swings from 8.1 to 8.35. Not a problem

FWIW mine swings from 8.1 to 8.5. Not a problem.

 

[Frick]

I don't have a mg tester but alk is 183 ppm on my Hanna checker.

I would track that. See if that is swinging. That is more dangerous IMO.

 

[dan-in-gr]

On my Neptune, it swings from 8.05 morning to typically 8.20 end of lights. Alk is 180 ppm on Hanna and is dead steady for past month with my CA reactor. Since cooler weather is here in Michigan, I have most windows closed and end of day is now about 8.15, I lost .05 pH with windows closed. Not bad.

 

[tmz]

The swing is natural. As photosynthesis stops ,the photosynthetic organisms stop using CO2 and respire some excess. Low CO2 raises ph and vice versa. Alkalinity is a measure of ions with negative charges( abut 96.5% of those in natural seawater are carbonate / bicrabonate which corals and other calcifying organisms use along with calcium for skeletal mass )that buffer the change. Steady alk is very important particulary for sps.

 

[REEF SMAC]

I think I would be more worried if my PH did not change throughout the day and night.