can you post a fts of your tank in its current state?

Agree 100%. Dying animals will do nothing good for a struggling tank.

Here's my before FTS and after and some closer pics. U can see all the dead sps in there

http://i1292.photobucket.com/albums/...ps49kdb2gp.jpg

http://i1292.photobucket.com/albums/...ps6tygd10f.jpg

http://i1292.photobucket.com/albums/...pskjxs52mi.jpg

http://i1292.photobucket.com/albums/...psunazdtt7.jpg

http://i1292.photobucket.com/albums/...psw3fpezet.jpg

id try removing the sandbed or most of it for starters

Probably not a bad idea. You also don't have the load or growth right now to worry about dosing, I'd turn it off and rely on good water changes every week to get nutrients down and maintain levels. Manually remove what you can for algae and blow off the cyano growing on the corals.

What's wrong with sandbed? Are those corals 100% dead already?

Sand is probably holding a lot of nutrients. And ya, I'd say most of those SPS are beyond recovery, unless you got them in a perfect system right now. Anything that has algae growing on it is gone, get rid of it. Anything dying is adding to the nutrient load. Again, get it out.

I always vacuum almost all my sand every single water change if that helps. Water from it is normally pretty murky. But I'm sure that's normal. My tank going to look so empty if I take out all my dead sps =(

Is vacuuming sand bed a good thing? I have never stirred up or vacuumed My 120 gallons sand bed I thought it just stirred up nutrients. I thruthfully don't know if it's good or bad.

I think you have to do what I did when I didn't know what was happening to my tank - stop absolutely everything that you're doing/dosing, and start a campaign of massive daily water changes. Change that water as fast as you can make it, up to and including at least 1 100% water change. Do this with a better salt than IO, something that mixes up with alkalinity closer to NSW levels.

Something is wrong in your tank, and by extension your water. You can bang your head against the wall trying to figure out what, but sometimes a 100% reset of the medium your corals are immersed in is the only way to completely eliminate all the unknowns.

I'd continue doing 20-40% daily water changes until the surviving corals stopped declining and started to improve, then I'd switch to once a week water changes, but bring the doser back online and adjust it every day as needed after testing alk, calcium and magnesium. I'd only switch to once a week testing after things definitively stabilized.

This saved my tank when I couldn't figure out what was killing my corals, and it saved it again after my tank nearly died during a renovation.