The bacteria that change ammonia to nitrite grow pretty fast, and can produce nitrite faster than the nitrite removing bacteria can grow. Even when you add the right species of bacteria, the ammonia removing ones get going faster.
The nitrite removing bacteria grow slowly. They are removing as much nitrite as they can (turning it into nitrate) but the other bacteria are growing faster. You added plenty of these when you added the right species of bacteria (Nitrospira), they just take a few days to get going, to catch up with the ammonia removing bacteria.
Here is how to handle this:
Do enough water changes to keep the ammonia and the nitrite under 5 ppm.
If the soil is slowing down the ammonia production add enough ammonia to read 3 ppm.
Do not worry about the nitrate.
This sort of level may plateau for a week or so. (though it usually does not last this long when you have added the right bacteria) Patience...
Suddenly you will find that the ammonia drops to 0 ppm overnight, and you no longer see nitrite.
Now it is cycled.
Test the nitrate.
Do as large a water change as you need to, then add fish, shrimp...
If you are not ready yet to add livestock, and the soil is no longer producing enough ammonia then keep adding ammonia to keep feeding the bacteria.
I have a very hard time telling the difference between all those shades of dark pink. Your nitrite might have been a lot higher (still darker pink, but I cannot tell!) and when you cut it in half (50% water change) it is still dark pink. If you cannot tell the color, then do a water change. When you can tell that the pink is a bit lighter, that is fine.
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