drywall and reef aquarium

[Salinity Now]

I guess it would depend on how much? I'd try to remove as much as I could anyway, with a fine netting or sieve. Also setup a sponge or some kind of mechanical filtration in your return line to try and remove as much as you can. I don't know if there would be any chemical reaction taking place with gypsum and your water. There may be a ph change, but I'm not sure? Good luck and keep an eye on it. For the future, I'd just tape some poly around the tank, or poly off the area that you're renovating to prevent it from happening again.