View Full Version : Testing PH, is there a better time of day?

01-27-2013, 12:29 PM
I cannot remember if PH should be tested after the lights have been on for a while or not. I got the 20 up and running on Thursday, tested water on Friday and PH was 8.2 and everything spiking as it should for a cycle. Added live rock on Friday and tested this morning. Nitrates, nitrites and ammonia at 0, but PH says 7.8.

Don't want to go trying to bring it up if I should be testing at a diff time. Lights are not hooked up yet, we plan to have that done today.


I'll get pics up soon

01-27-2013, 12:35 PM
Its at lowest for a few hours when the lights come off and highest when they turn on

01-27-2013, 12:38 PM
Ok great. I was thinking that was the case. I just couldn't remember.

static reef
01-27-2013, 01:16 PM
i set up my tank lights to come on in the evening and the fuge lights are on the rest of the time, so that my i never get the ph swininging

01-27-2013, 06:44 PM
Where in the house is your tank? CO2 is heavier than O2 so it sinks. If the tank is in the basement, pH will be lower there. pH drops at night and goes up in the day.

01-27-2013, 09:34 PM
It's on our main living level. Basement would be no fun! I've got the lights up now so I am going to test again and see how it's doing

01-27-2013, 09:52 PM
Randy Holmes-Farley states;
The pH of seawater is typically stated to be 8.2 0.1, but it can vary as photosynthesis consumes carbon dioxide locally and as respiration produces it. It also varies by latitude and is often lower where there is upwelling. It is also a function of depth for a variety of reasons, including photosynthesis near the surface, decomposition of organics in the mid-depths (dropping pH to as low as 7.5 by 1000 meters), and dissolution of calcium carbonate in very deep water (raising the pH back up to around 8). In closed lagoons, the pH can cycle from day to night just as in a reef aquarium, rising several tenths of a pH unit during the day. In special circumstances, seawater can be much lower in pH. Seawater in mangroves where highly reducing sediments are present can reduce the pH to below 7.0. In the open ocean, where there is a much larger volume of water containing buffers, the pH fluctuates little. As humans have added carbon dioxide to the atmosphere, more carbon dioxide has also been added to the oceans, with a consequent drop in pH. This is one of the impacts humans have had on the oceans that concerns ecologists in terms of its impact on calcifying organisms, especially on coral reefs but also on other systems involving such organisms as foraminiferans, which have calcareous skeletons and which are important links in many marine food webs.


01-27-2013, 10:59 PM
Excellent info murf. Thank you. I'll feel better knowing a fluctuation is normal