A pinch
There is approximately 10 ml in 2 teaspoons - that is a tiny fraction of gallons.
If I did my math correctly I believe that you would need 150 teaspoons
There are approximately 183.33 gallons in 11,000 teaspoons.
3,072 teaspoons is four gallons.
51 US gallons is 39,168 teaspoons
0.1 tsp, because one gallon is one tenth of ten gallons, so you need one tenth, or 0.1, tsp.
1,248 US teaspoons = 1.625 US gallons.
500 US teaspoons = ~0.65 US gallons.
36 US gallons = 27,648 US teaspoons.
500,000,000 US gallons = 384,000,000,000 US teaspoons.
That is 2,112 teaspoons.
That is approximately 1,920 teaspoons.