PH suddenly at 7.0

Normally I check my PH every day or too , but I probably haven't checked it in 4-5 days and all of a sudden it's at 7.0 when its normally its 8.2-8.4I run Kalk on a normal basis in my ato and have made no changes recently. The only real changes in the past 4-5 days is that we have shut our windows but a 1.2-1.4 drop is a lotI have checked with both a test kit and hand held monitor and strangely enough the corals look fine currently have nice PE on my SPS

 

What is your alk.?

 

Alk is 9.0

 

Tested again this morning with the PH meter after recalibrating and it still read 7.0Retested with a kit and it showed 8.2. Whew!!!I think what happen last night is in my panic I only added 4 drops instead if 5 with the API kit. Definitely something wrong with my handheld , maybe a bad sensor ?

 

My vote is time of day you did the test. During the day the pH is higher, during the night pH is lower.

If you have a sump etc, this is the reason you run a reverse lighting cycle which keeps pH swings to a minimum.

To be consistent with testing its also good to do it at the same time of day. Not just when you have time.

 

Ryan is correct. However, it shouldnt swing that much. I think it was just a combination of everything.

 

Mine used to swing huge when I had the sump light on a the same time as the display tank and then it all off during the night.

It would easily go from 8.2-7.2 overnight. Was freaking me out big time until I was told to do a reverse lighting cycle, hasn't budged from 8.2 since.

 

It actually probably didn't swing at all and was just due to a bad sensor, may have to replace it