Fast evaporation or problem?

I have a 125g reef w a40g sump/ref. Drilled system. I don't know what's happening lately the float on one corner of the overflow can't have the lid on anymore without water getting to high. At the same time in my return well my ato seems to run way too much water is " disappearing" fast every day. Skimmer likes to overflow at night as well. Lots of issues I know so any info would for sure help. Thanks