What is your pH in tap water when it comes out of the tap
and when it has sat for 24-48 hours?
A quick note about this. When you use crushed coral to help change the pH it takes a decent amount of time for the minerals to effect the water, and when you change the water 50% every week which is a GOOD thing, you basically remove whatever has begun to break down in the water though.
This is what I use most often. The reason is because my water basically is at ZERO kH which is not perfect for many of my fish.
Every time I add the new water I add the Kents. Just a minimal amount, the directions tell you how much to add to get it to the number you are looking for. You start with one tsp per [Edited] 20-30G , then test the water after an hour and see where it sits. Yours would be 1/3rd of that - 1/3 tsp for 10 gallons. If you needed to only boost the kH like a half degree then use half of the 1/3 tsp.
If needed - I personally wait a few hours usually before adding the next dose so it is a gradual change for the fish. If you got to 7.2 that would be in the 7-7.5pH range for snails.
***Then just periodically test the tap water and see if it ever changes pH, and compare to the tank just to get a feel for where is rests at after weekly doing water changes. My minerals are used up by the plants I guess and I often need to add a little more to the tank.
Then you will know how much to add for every 5G bucket of water for each water change.
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Specifically in one of my tanks, it is highly filtered and doesn't get as many water changes, and that is the one I need to check on most often. (also my city tap water changes at least 2 times a year because the water comes from snow melt in a lake and when that runs low it comes from the reservoir which has a basin of hard rock and the difference is around 6.5 to 7.5pH always a guessing game!)
It is fine to use in freshwater tanks as well as SW /marine tanks. You will not need to add as much and it will not raise the levels like SW.
https://kentmarine.com/products/kent-superbufferdkh.htm
Alternate future idea -
You might also consider using Ramshorn snails in a cool color like blue, red or orange and they repopulate frequently and do not live as long as Mystery snails or Nerites.
That way you can keep them in a lower pH tank as a Betta might like and not be as worried. Use the MS and Nerites in a tank with fish which prefer a bit higher pH (use the kH buffer and keep them all happy.