Ph keeps rising - help!
Hello everyone I have 2 * 18 gallon aquariums. One is a year old and one is three months old. Both have fully cycled (Started the second one with gravel from the first one). They are lightly planted aquariums.
Originally I had trouble with my aquarium becoming more acidic over time. I had to add shells to help it stabilise, and I purchased device to measure pH constantly.
Now I am having the inverse challenge where my pH keeps rising. In aquarium number one the pH is at 7.6, though it was at 7.0 when I finished my water change 2 weeks ago. I removed all of the shells.
In aquarium number 2 the pH Was 7.6 after my water change and is now 7.9. I added a large piece of driftwood to aquarium last month to try and stop the increase. Only things in that aquarium are the gravel, pieces of driftwood, some plants and the fish and snails.
Fish aquarium 1: 3 Cory catfish, 3 White cloud Mountain minnow, 1 Harlequin rasborra, 2 clown killifish, 2 snails.
Aquarium 2: 4 cardinal tetra, 5 ember tetra.