Get a good sand bed crew I have a slider conch, 6 Tonga snails and a sand sifting Gobi it is a orange diamond Gobi. zeovit is good for combating phosphates dinos are caused mostly from organic tissue dieing and breaking down in the tank. you can try these 3 animals they seem to work great for me if some thing dies the Tonga snails are on it in a snap and you can find it in no time they will congregate at site of death and will even pull it into the open some times if the dead critter is small so all Tonga's can eat. hermits and shrimp get the leftovers it seems. by the way if your snails, shrimp and corals are dieing then they could be causing the dino troubles. Check your water for copper you may have some rock that was treated with copper.

1. get tank parameters in check and in order before doing any thing else get a good cleanup crew and a sand bed maintenance crew.
2. once cleanup and sand bed crew are in the tank and do OK. change light cycle to 2hrs on 2hrs off 2hrs on 2hrs off for 8 hrs a day for a couple weeks leave all lights off at night. the fish will adjust and this will help combat dino's you may have to do this for some time till dino's are gone.
3. do water changes every week 10% will do till dinos are gone then you can go to every 10 days.
4. keep a log for everything to do with your tank parameters, equipment maintenance live stock added live stock deaths everything that happens to the tank should be logged. You can build a log in excel so it's not difficult to do.
I don't know what parameter you test for but you should buy all test kits and test and log them all each and every time you test for some thing even if it was only one test. This can help you solve some problems Dino's will appear about 1 day after something dies in the tank.

Bill