What do you put in the toilet tank to get rid of the brown slime?

https://www.youtube.com/watch?v=t8YWYyUUmfM

This suggestion will only work for a short time. Pour a bottle of vinegar in the water tank, best to do it late in the evening so the toilet will not be flushed for several hours. Vinegar is safe for the drain system and it will kill most algae you find in toilet tanks. Since vinegar is cheap and safe you might need or want do this more than once to solve the problem. I had a similar problem, vinegar fixed it but I had to do the flush job 3 times. DO NOT get that slime on your skin, you have no idea what may be in it.

try white vinegar 100% add the vinegar after the flush let it stand 1 hr. And then flush. Do this once a week and u will see the difrence. It does not damega the pipes nor the mecanism in the water tank. Good luck

2 liter of Coke? It works in the toilet itself, might work in the tank also, pour it in and let it sit for an hour or so then flush and see what happens