I'm into this hobby over 6 years but sometimes i feel like I'm new. My old 90gal.came with sump from my LFS
. It was the package. Sump was 24/12/16. I think it is 20gal. Simple just 1 baffle in the middle with 2" space from the bottom. so the level in sump was the same in all lengh.So when I was loosing water thru evaporation I had a lot of tolerance. Yea the salnity would go up but I could go from 8" to 2" of water level. Now I see thouse design and I do not understend. When you have first baffle like 9" high from the bottom up, water has to go over that. What happen if the water level goes down thru evaporation? How that water goes over? Will it take more water from the tank to the point there will be no water drain thru overflow? I know it is stupid question but can somebody explain this to me? As I understend water must be all the time over that baffle, like 2",3" so it can go down but still over first baffle. Is that right? Please let me know.Thanks.