I have an established tank, I want to add some discus, I am having trouble lowering my pH enough. I have killed some of my kids fish before due to pH swings. I have done reading and watched videos that explain the relationships between pH and kH and still can't seem to make it relative to me. This is annoying because I am typically quite scientifically minded. Below are my current water parameters. 5 days ago I started adding Seachem Discus Buffer to lower the pH in preparation for adding some discus.
900mm x 390mm x 400mm approx 120L.
average of 10cm large grain gravel
5 different styles of plant (picture attached)
1 large lava rock
2 grey rocks (not sure how to describe them)
1 x muscle shell (he died along time ago, cleaned the organics out, liked the look of his shell)
EHIEM classic 2213 canister filter
50%-70% water changes weekly with a glass scrub, gravel vac and flirt floss change once a month
lit by 61xm 20W T8 6-10hrs per day
3 x Juvenile Bosemani Rainbows
3 x Cato River Rainbows
4 x Pacific Blue eyes
2 x medium-large mystery snails
TAP Water: (which was only treated with chlorine neutraliser prior to this effort to lower the pH)
Dosing over the last 5 days:
Each day I have added 1.5 tsp of Discus Buffer, which has slightly lowered the pH each day.
I was hoping to add 2-3 discus (juvenile to start) and a school of 10-12 glass catfish.
I am aware that consistency is much better than perfect values.
Any advice at all will be helpful.