Hi..

Would that person go into greater detail the principles
and practices of doing such, for me, please.

Well, not that person but..

Chinese and Indian tea for example have several ingredients
but I'm not sure that they have a _general_ benefit to any
fish and (or) plant..

Benefit for example might have tannins (tannic acid) while
caffeine were poison to fish.

I would recommend complete leafs, no broken tea or tea
powder. A tannin-rich sort of tea were Darjeeling Tea. The
best tea I know were a Darjeeling spring tea. Darjeeling is
no dark tea so don't confound "colour" with benefit.

How to prepare tea for 50 litre / 13g:

1: Give 5 teaspoons of that tea leafs in a warm teapot,
2: add 3 cups of boiling water and wait 90 seconds,
3: remove that water, its caffeine were no good for fish,
4: add new hot water and wait 8-10 minutes,
5: fill that tea in a bowl and let it cool down,
6: then remove the tea oil with a sheet of paper from the
surface,
7: use that tea for your tanks.

Why should one take leafs instead of broken tea or tea
powder:

# Caffeine (and pesticides) leave the tea very quickly
through the surface of the leafs while tannin need much
more time to leave it, a good way to separate caffeine and
tannin
# "Injured" (broken or powdered) tea would loose more or
less of its tannin in the same time as its caffeine.

HTH.
--
cu
Marco