Please help--snail died and then I made things even worse...

[Zylumn]

sharuq1 Sorry to hear about the problems your having. I wish I was closer to help but will chip in my 2 cents worth.

To me it sounds like with your ammonia high you are going through a cycle. This could have been brought on by the 100% water change. My suggestion would be use only R/O water prepared hrs in advance with exact tank temp and salinity. Change out a max of 2 gallons per day at one time or 2 x 1.5g per day. Feed your fish sparingly (maybe every 2 days) or feed then do water change and get out any extra food.
Good luck.
Kevin