Alkalinity crash


New member
I tested my tank last week (9/8/12), left for Boston the following day and just returned yesterday. My wife was taking care of feeding the fish, monitoring the temperature, filling the ATO and changing the socks.

I decided to test things today and it appears that my pH has spiked and the Alk has crashed. I thought it might just be easier to post screen shots of the app I use as opposed to typing everything out.

What happened and what is the correct course of action. When I came home last night I noticed the windows are open since it's cooled down a bit. I don't know what day she opened the windows and can't get a hold of her until she gets home from work tonight.

I've read that opening the windows can cause a pH spike, but this seems excessive. Nitrates and Phosphates are both 0ppm.

I am running GFO and don't dose anything yet. I used to dose vinegar about a month ago, but stopped because my levels came down to 0 and I began getting a lot of bacterial growth in the tank.

All inhabitants seem to be doing well. I have one fire fish, a few small colonies of zoanthids and one purple hammer coral.

I rechecked the alkalinity using a new cuvette and a fresh battery and received the same result.

Alkalinity (Hanna Checker):


pH (API):


Calcium (Red Sea Pro):


Magnesium (Red Sea Pro):



Premium Member
8.4 is a very good pH for a tank, and that range is about what I'd expect if the windows were opened in a room. I suspect the drop in alkalinity is due to normal consumption, which picks up as the pH increases, but I'd watch, just in case.


New member
Here is my newest round of testing. Anything I need to worry about bertoni?

pH = 8.3
Calcium = 355ppm
Magnesium = 1,420ppm

My Calcium has been low since I started the tank. I have one turbo snail that hasn't been looking too good for the last few days. He seems to be sitting in one place and isn't fully attached to the glass. My wife said he was moving around yesterday and then just stopped again.

Other than that, everything is doing well.


New member
I would like to know as well, currently I am keeping track and notes via notes on the iPhone. It fails, but works.


Still Learning
I used to use the hanna alk checker until recently. I noticed when I was getting close to the bottom of the color solution, that I was starting to get false high numbers. For example, 170 ppm alk when my backup (Salifert) was registering closer 155 ppm alk. My system showed the signs that it was closer to the Salifert reading. In case you want to change anything, try another test kit and see if those readings are accurate. Hope this helps.



New member
WickedBlue is correct, it's aquaPlanner Pro. I think it was $3 if I remember correctly. I went with the Pro version because of the ability to sync via iCloud with my iPad.

Anyone have any thoughts on what I should do next about the low Ca and Alk?