[AquaticLife] pH change
It all depends on your starting baseline and then the ecology of the tank will affect the pH after that. The “normal” ecology of a tank will ALWAYS lower the pH over time.
If you have rocks that leach calcium carbonate and/or other minerals, this can keep the pH stable or raise it.. or if you actually add your own KH booster like baking soda to help raise and stabilize the pH.
Your fishes poop (breaks down and releases carbonic acid among other things), pee (acidic) and the bacteria that handle nitrification and other biological issues in the tank will usually use up KH and other trace elements which causes the pH to go down.
Doing PWC’s is what removes the pollution and also replaces the trace elements.
In your case, it would seem that you either have something in the tank that is leaching a little hardness or something basic (opposite of acidic) that is raising the pH or it could be your baseline of the tank is higher than 7.4 and when you didn’t feed them for several days, the buffers in the water was able to buffer the water back up a little.
Thinks like keeping the gravel clean and the filters cleaned regularly will also keep the pH more stable since you won’t have as much decaying detritus/mulm that would lower the pH as it decays.
Last but not least, the time when you check the pH can be a factor if your tank has plants or lots of algae. During the day (lights on), the plants are using up a lot of the available CO2 during photosynthesis and as the CO2 goes down, the pH will rise. If you check a planted tank (or a tank with lots of algae) after the lights have been on all day, the pH will be higher than if you check it in the morning before you turn on the lights. After being dark all night, the CO2 level will have risen which will have lowered the pH.
Lenny Vasbinder Fish Blog - http://GoldLenny.blogspot.com
Category: Philippines Internet Koi Society
