I recently restarted my 3.5 gallon as I was starting to miss having a betta. I used already cycled ceramic rings and floss from my 1 year old 29 gallon to fill the HOB and then ran it on my 2 year old killifish tank for 2-3 weeks before setting the tank up. To make sure it "instantly cycled" my betta tank, I tested my water 24 hours after adding the betta (I added him wednesday) and then again tonight (48 hrs). I have never had a problem with pH as my tap was always 7.8 and the tanks were all 7.8 so to be honest I haven't tested my tap since this time last year. I used a new piece of driftwood for this tank and for a week it leeched some tannins and the tank was looking blackwater. I did a 90% WC while my betta acclimated. Now, i need to retest the tap which i will do tomorrow, but given that it is still 7.8, and my pH test is showing 6.8-7.0 for the betta tank, how should I go about water changes without shocking my betta? I think the low pH is because of the driftwood tannins given how small the tank volume is, would you agree? And given that logic, shouldn't my pH theoretically level back out to tap levels over time once the driftwood is done leeching? Again, I've never had an issue with low pH in a tank or had to worry about pH differences between the tap and tank so I'm not sure how to approach this...there is the possibility the pH of my local water supply changing over the last year...in that case I will post an update about that here and that will be the end of the issue lol.