Incubator

Don't you love conflicting instructions? LOL Yes, you can open your bator to add water and candle. At lockdown the less you open the better, as it does higher the probability of interfering with hatch, but the first 17 days it's not a problem. When I candle I remove one egg at a time and close the bator in between, but the recommendations I was given when I started hatching was keeping it limited to 1/2 hour.

I do want to point out though that the directions that bators give you for filling water wells is not necessarily what the individual hatcher needs. One person that buys that bator may live in a more humid area and need less water in the bator than someone in a dryer area that buys the same bator. The best thing to do is to have a good (fairly accurate) hygrometer in the bator to monitor what your humidity is. A good share of people shoot for 40-50% humidity then there are those of us that do the dry hatch for the first 17 days. Either way you should check the eggs air cells periodically to check for proper growth (that is why we control humidity-so the eggs loose the right amount of moisture and weight.) At lock down the humidity needs to be highered. The recommended is at LEAST 65%, I personally shoot for 75%.
During the hatch if you are just guessing and not monitoring the humidity/air cells and the egg does not loose enough moisture the chicks can drown at hatch. If you loose too much moisture they can become shrink wrapped at hatch.

 

Also it sounds as though it is a still air bator. Most manufacturer's instructions give a recommended temp of 99.5F for the bators and in reality a still air incubator should run 101-102 during the incubation.

 

The same amount of moisture in the air will be a higher relative humidity in lower temps. Leave the incubator on to get a true reading of incubator conditions

 

24hrs is pretty average