I am fairly new to reef keeping, I have had a saltwater tank for about a year and a half now. My current system is about 120 gallons (60-24-18)+sump. Everything was doing quite fine. I added some soft corals to my tank, two different kinds of leather fingers, one with fatter branches and a darker pinkish-purple color and another with skinny branches and a light pink color, a leather vase, a colt coral and a small piece of rock with about 5 mushrooms on it. I was getting a lot of corraline alge growing everywere and mushroom polyps started appearing on other pieces of live rock. One night with my flashlight I noticed about 9 snails on my rock this quickly turn into about an army of 200. Anyways my corals did well for some time and then they started to not come out and started wilting next thing i know they are getting lessions on them and starting to dissinagrate and they get a brown algee growing on the stems. Only two at first one finger and the vase. About a month ago I did some modifications to my tank. I put everything into my 55g and emptyed my 120g I put a overflow in the corner and built a sump. I have a Auqamedic OR3500 return pump that returns into a 4 foot spray bar which was covered with coralline algee. After I set everyting back up I made the mistake of filling the tank up with tap water as I don't have access to R/O water. I ran the tank for only 2 weeks with nothing in it except salt (coralife) and some Seachem chemicals and some live rock. I then added the rock, fish, and corals back in. the two corals still very sick. The coralline algee on my spray bar in is white posibally bleached by the tap water? My finger is falling to pieces and my vase is starting to dissinagrate at the stem and fall of the rock. Now my other finger is getting quite a large hole in him as well and brown algee growing on his stem. My colt is shrunk up very small and even my mushroom polyps are small and not doing well. I do a 25% water change monthly, I fill buckets with tap water and let them sit for 2 days to evaporate the clorine before adding salt. I have always used chemi-pure and in my new sump the overflow drains into a chamber of bio-balls and through a 500 sponge and then 4 chemi-pure's. I have 2 marine-life aqutics aggressor-90 skimmers in the sump. NOT SURE ABOUT THOSE BIO-BALLS at the moment? Is it safe to keep sick and dissinagrating corals in the tank? I have tryed Seachem Reef Dip on the corals a number of times but I don't think it does much of anything. Half of my colony of snails is on my sand bed in the daylight? Many upside down and a lot of empty shells they are starting to die off is this normal? How long is their life span? What chemicals should I be using? Any help would be greatly appreciated. Thank you!