Acceptable Ph swing??

kwandrsn · Jul 10, 2015

Ok I have a 57 gallon tank with a 20 gallon sump. I have to open the side door to my stand during the day and also have a couple 4" fans inside the stand to help stop condensation. I close the stand door at night because my scrubber lights are on a reverse schedule and the tank is in our bedroom

I noticed my Ph levels gradually rise throughout the day. Im running a kalk stirrer as well.

I am wondering how much of a swing is acceptable. My ph normally runs 8.2 to 8.3 but because it got to 8.4 my controller shut the stirrer off (its set at 8.3 with a 0.1 hysteris) and my ph was 8.0 this morning. I changed it to when it wont shut the stirrer off anymore. This was the first time this has happened...

Its back at 8.39 now with the side of the stand being open all day.

NanaReefer · Jul 10, 2015

Totally normal for ph to rise during the day and fall at night. Your numbers are spot on. Only time you need to be concerned about ph is if it is above or below and stays at what is not acceptable.
Stop chasing your ph [emoji6]

kwandrsn · Jul 11, 2015

It dropping to 8.0 then back up to 8.4 is what concerned me. I dont know if it was because I had my controller set to shut the stirrer off at 8.4 and back on at 8.2 or not.... but even though it came back on at 8.2 my ph still got down to 8.0

ngvu1 · Jul 11, 2015

Mine is like this all the time. I run the sump light in reverse cycle but still, the PH swings. I am not sure I want to watch the PH any more

kwandrsn · Jul 11, 2015

Wow thats crazy.... I never paid any attention to my old tanks ph... seemed to stay at 78 when I would check it with an api test kit.... this tank started at 7.8 but when I hooked the kalk stirrer up it shot up to 83 range

Downbeach · Jul 11, 2015

Here's Randy's article on the subject:

http://reefkeeping.com/issues/2007-05/rhf/index.php#6

kwandrsn · Jul 11, 2015

Just seems like 8.0-8.4 is a pretty big swing

Randy Holmes-Farley · Jul 11, 2015

kwandrsn said:
It dropping to 8.0 then back up to 8.4 is what concerned me. I dont know if it was because I had my controller set to shut the stirrer off at 8.4 and back on at 8.2 or not.... but even though it came back on at 8.2 my ph still got down to 8.0

The magnitude of the daily swing is not an issue, as long as the extremes don't go outside pH 7.8 to 8.5 (IMO).

This has more:

http://reefkeeping.com/issues/2007-05/rhf/index.php

FWIW, more aeration will reduce or eliminate the swing, but natural lagoons also swing daily.

kwandrsn · Jul 11, 2015

Yeah its between 7.8 and 8.5 barely but it is

Randy Holmes-Farley · Jul 11, 2015

kwandrsn said:
Yeah its between 7.8 and 8.5 barely but it is

For years my tank ran at 8.35 to 8.5, so the high end of OK is not a concern. The problem there is that precipitation of calcium carbonate on pumps and such becomes faster and faster at higher pH. In that regard, a pH rise of 0.3 units is equivalent to a doubling of either alkalinity or calcium.

jeffp1 · Jul 11, 2015

My tank has been running from 7.65 in the morning before the lights come on to 7.9 in the afternoon. I have good growth on my SPS and LPS both. I calibrated my probe and handheld meter this morning and Ph was 7.65. My cal. is 500, ALK 8 and Mag. is 1450. I am starting to dose Kalkwasser today through my ATO. Do you see any problem starting the Kal. today? Have made some big water changes last couple of weeks due to small cyano problem. I am guessing that is why cal and mag. is high.

kwandrsn · Jul 11, 2015

I just done a water change a couple days ago... I didnt notice the 0.4 swing before that. Would that have anything to do with it. And after the water change all the cyano on my sand went away. But I do have cyano on my scrubber screen (tank has only been set up a couple weeks)

Randy Holmes-Farley · Jul 12, 2015

jeffp1 said:
My tank has been running from 7.65 in the morning before the lights come on to 7.9 in the afternoon. I have good growth on my SPS and LPS both. I calibrated my probe and handheld meter this morning and Ph was 7.65. My cal. is 500, ALK 8 and Mag. is 1450. I am starting to dose Kalkwasser today through my ATO. Do you see any problem starting the Kal. today? Have made some big water changes last couple of weeks due to small cyano problem. I am guessing that is why cal and mag. is high.

I don't see any reason to not start kalkwasser.

Randy Holmes-Farley · Jul 12, 2015

kwandrsn said:
I just done a water change a couple days ago... I didnt notice the 0.4 swing before that. Would that have anything to do with it. And after the water change all the cyano on my sand went away. But I do have cyano on my scrubber screen (tank has only been set up a couple weeks)

Not likely that the swing is larger due to the water change.

The daily pH swing is a function of alkalinity. Higher alkalinity means a lower swing. Higher overall pH also means a lower swing. More photosynthesis means a larger swing, and more aeration means a smaller swing (complete aeration will nearly eliminate any pH swing unless your home air varies in its CO2 content).

kwandrsn · Jul 12, 2015

Well I have a dct8000 return and 2 jebao wp25s in a 57 gallon tank and the drain and skimmer and scrubber in the sump so ive got lots of water movement. I have 3 small 4" fans in stand circulating air because im having a bad condensation issue. I still have to open side door of stand during the day because the fans didnt stop the condensation completely

Our house have central heat/air so I am not sure about co2 content

Randy Holmes-Farley · Jul 13, 2015

People think they have better gas exchange than they really do. CO2 exchange is not trivial. Just the fact that there is a change in pH from day to night in most tanks proves it (unless the tank is in a closed room with more people at night).

kwandrsn · Jul 13, 2015

Its in a closed room... our bedroom (which includes the master bath and walk in closet as well) but we are in it more at night but we are still going in there off an on during the day as well