Correct PH tabs, what do they do?

I have this product in tablet form called "Correct PH"
It says on the package "a PH level of 6.8-7.2 is the desired PH Range,
Correct PH helps to obtain this neutral PH by gradually buffering the
water.
Buffering the water helps lower harmful ammonia levels"

I thought buffering the water is like raising the PH, my PH is already high,
7.8
How do I lower it? Will these tabs work?

This is a new tank setup, 90 gal, no fish in yet, i jumpstarted the biobugs
by squeezing in
a dirty filter sponge from an already cycled tank. Tank was a mess for 8
hours, but the water
is all clear now. Here are the stats;
PH 7.8
Ammo 0.1mg/l
Nitrite 0
Nitrate 5mg/l

Wondering if i should add in my 9" comet, he comes from a 35gal tank that is
already cycled but
PH is low 6.0. I worried if the sudden change in PH could hurt the fish?