If you’re not in lockdown, and your humidity is too high, then stop putting any water at all in. You don’t need to maintain a 50% humidity during the first 18 days. Whatever your ambient humidity is should be fine unless it’s down in the teens. I only add water if my humidity goes below 20%, which is rare.
Instead of trying to maintain a set number, allow your parameters to be between 20 and 55 or so. That will be a lot less stressful for you.
Now, when you get to lock down, that is different. Then you don’t want it to go below 65%. Keeping it high is usually easy enough. Add a wet sponge and periodically squirt water onto the sponge through the vent hole (using a squeeze bottle with a tube attached).
And just for info, the eggs always need oxygen. So if you are trying to control humidity by opening and closing vent holes, make sure there is always at least one hole open.
Best wishes!