It varies. Add about 1 tsp per 10 U.S. gallons (roughly 4 L). Then give it about 20-30 minutes to circulate. Then test your pH. Continue to add at that rate until the pH is in the 8.0-8.4 range.
It can take time... this isn't an exact science. It will end eventually. Keep researching your fish, plants, checking different decor ideas to fill the time.
I know, I'm with you. I'm on day 33 of my cycle (not counting a previous tank I tried to cycle for 6 weeks before totally giving up and trying a brand new tank). Think of how happy our fish will be going into a tank without ammonia! (at least that's what keeps me going). It'll happen eventually, hang in there.
The only thing I did which wasn't by the book was 'very gently swish' my sponges around in a bucket of tank water during a water change to get rid of the slime and sand dust that had built up.
I have plenty of both bacteria but can't process nitrite in 12 hours - takes about 16 hours and I have had little change for 2 weeks
I added a few more ceramic beads to my filter yesterday so we'll see what that does....
Oh and I bought one of those magnetic glass cleaners at the same time - retail therapy
lol i keep buying fake plants and i have even made some tank decorations out of pebbles and aquarium sealent lol anything to stave off the urge just to shove some fish in, i have the patience of a gnat!