I have a 55 gallon tank and the hood of the tank in the back is open on both sides and there's salt that forms on there is there anyway to close it up ? or leave it as is ? would this lower my salinity at all ?
IMO I would go without a top or use egg crate.
I wouldn't close that gap up (more oxygen flow), so leave it.
No it won't lower your salinity, when cleaning it off try not to let it fall back into the tank.
To clean it off take a wet rag and wipe it up. With the rag being wet it will dissolve the salt again. As mentioned above try not to let the salt fall back in the tank. If it lands on some coral it could damage it.
Take a piece of wax and vigorously rub the wax along where you have salt creep. For some reason, this prevents salt creep. I dont know how or why it works, but it does.
that wax tidbit is interesting but do put the creep back in your tank (in your sump so it wont land on anything) because the salt creep isn't just salt, it has calcium and other trace elements in it, the likes of which is beneficial to your tank and maintaining the mineral equalibrium<spelling?.