I have (had) a 3.5 inch Crocea. Went away for the father's day week, when I returned Sunday night my sump was half empty (overflow clogged), floor was flooded and my automatic topoff was adding ro/di water for I don't know how long. I usually keep it at 1.025 but it was down to 1.018. It took 2 days to get it back to normal. I found a Peppermint Shrimp dead in the sump and my clam was not looking too good. Well the clam died last night. So I guess my question is did the low salinity do it, is that too low for clams and other inverts. I know they are affected first but not sure if 1.018 would do it. All fish and corals seem fine, as do the coral banded shrimp, brittle star, cucumber and assorted snails.