I have to buy some black fungus removal for my pool tiles and was wondering if I could put some in a spray bottle and spray the gyproc ceiling where water leaked in.

The leak is fixed but I have to kill that growing fungus.

Could I use the pool black spot fungus removal on the ceiling?

What's the best pool fungus removal to buy?

Spraying it likely will not hurt anything, but without moisture, the fungus will die anyway.

20 minutes ago, Yellowtail said:

Spraying it likely will not hurt anything, but without moisture, the fungus will die anyway.

Humidity is pretty high here at the moment.

What brand antifungal would you recommend?

Just now, carlyai said:

Humidity is pretty high here at the moment.

What brand antifungal would you recommend?

If it were the humidity, the whole ceiling would be black.

If the leak is fixed, and it is truly dry, I would wipe it with hydrogen peroxide and paint over it.

Spray some diluted bleach on it

For that ceiling, I'd do:
Fix leak and dry.

50/50 white vinegar + water

Spray a light mist, don't saturate the gyproc.

Leave it for about 5–10 minutes.

Wipe firmly with a damp cloth.

Follow with a clean, slightly damp cloth if there's residue.

Dry the ceiling thoroughly with AC/fan.

Don't mix the vinegar with bleach or any pool chemical.

4 hours ago, CallumWK said:

Spray some diluted bleach on it

+1 here. I've never had good luck with acetic acid (vinegar) on most molds.

I use it (vinegar) to dissolve scale because it's a weak acid. It'll dissolve Calcium Carbonate, which is the prevalent component of most scales. It won't kill a lot of living stuff, because it's basically the remnant of fermentation. And an ingredient in a lot of food recipes...

Bleach is very toxic to most living stuff and it will also get rid of the black color. Of course, you have to be careful with it because it is pretty toxic (though a lot of municipalities use it to treat tapwater- in low concentrations, and survivalists use it to treat drinking water with a few drop per gallon, then letting it sit so the bleach evaporates.)

Edited August 17Aug 17 by impulse