pH in quarantine

[jaws789832]

Hi all and thanks for everything you do. I have 2 blue reef chromis in a 28 gallon jbj aio tank. I am just observing now no medications they have been in there just over 3 weeks and everything is looking good. I use the stock filtration with a pad, ceramic rings and carbon at the moment. I have medications on standby but haven't had to use them as of yet. the tank is bare bottom with 2 6" elbows for hiding. The fish ate from day 1, frozen and live black worms (they wont eat pellets or flake though, which when I try I have to syphon out). . I change the water in my DT (about 20 gallons) every week then use that water to change the QT (about 13 gallons). My problem is with PH. The PH in the DT is around 8.1 (at night) and 8.3 (during the day). The PH in the QT drops to about 7.6 pre water change. After water change it goes up to about 7.9. I assume its so low in the QT due to lack of sand and live rock (nothing to buffer and maintain higher PH).
1. How bad is this for the fish in the QT that the PH jumps that much in a few minutes? They don't seem to mind much but I am just not sure if its overall bad for their health.
2. What would be the best way to keep the PH in the QT tank higher? I thought about adding the alkalinity part of 2 part. Doing like a capful every other day (test to see what I actually need). I also thought about adding some of the 2 part to my makeshift ATO (a 2 liter bottle full of RODI stuffed in the back of the tank that when the water drops below opening it pours out until the water level seals up the opening again), that way it slowly gets added as the water goes in.
Any suggestions? and thanks again

 

[Humblefish]

1. How bad is this for the fish in the QT that the PH jumps that much in a few minutes? They don't seem to mind much but I am just not sure if its overall bad for their health.

IME; fish aren't overly sensitive to pH swings, however your 7.6 is close to the minimum threshold of 7.5.

2. What would be the best way to keep the PH in the QT tank higher? I thought about adding the alkalinity part of 2 part. Doing like a capful every other day (test to see what I actually need). I also thought about adding some of the 2 part to my makeshift ATO (a 2 liter bottle full of RODI stuffed in the back of the tank that when the water drops below opening it pours out until the water level seals up the opening again), that way it slowly gets added as the water goes in.

You can dose "baked" baking soda to raise pH (see below). I would go ahead and raise your QT to match the DT since you are needing to dose anyway.

Spread baking soda (NOT powder) onto a clean baking sheet, and bake at 300F for 1 hour. This process drives off water and carbon dioxide from the baking soda, and the result is an effective pH buffer. You will need to experiment (start with a very small amount) to determine how much is needed to raise your pH to the desired level.