Huge ph flucuations with (co2 day) then (oxygen night)
I completely understand ph is going to change with co2. But I'm kinda worried about how much it changes by day and then overnight. I'm sure the up and down has to be hard on the fish. For the longest time, I never ran an airstone at night. My ph stayed around 7.2. But realizing how hard my water was from tap (TDS was close to 300, kh was about 12-15), I started mixing RO water with my tap water on weekly WC (50% because I dose Fert using EI method). This helped bring that hardness down a bit over 3 weeks of slowly mixing in more RO (TDS 95, kh & gh at 5), but of course, with a lower KH, I needed to increase my Co2 as it was too low. I did this over a few days until I hit about 30ppm on Co2.
I started wondering if I increased it too fast. I checked the ph last night before the co2 cut off (I have it running on a timer along with the lights). I was expecting a ph drop, but I didn't realize how much. My previous 7.2 was now 6.6. I thought that maybe I could run a little airstone overnight. Hopefully that will get me a little to 7.0 and we will live happily ever after. I put it on a time for overnight.
I get up this morning and decide to check that ph, and now it's back to 7.4. Which 7.4 is completely fine to me. Drop checker is a turquoise color. However, going from 7.4, to 6.6, and then overnight, back to 7.4. I'm concerned if I were to do this on a daily routine - 7.4-6.6 rotation - how is this huge fluctuation affecting my fish?
Anyone else run airstones at night to gas off the co2? Do you have such a huge change in ph?