Questions - Need some input

OK after three months of fighting 80+ Nitrates I am making some changes. This tank (125) was a former fish only saltwater tank and am suffering from the poor maintenance of previous owner. Although i scrubbed the live rock and cleaned half the sand, I kept the bio balls as they were thinking i needed the bacteria for seasoning the tank. Since i am still struggling with Nitrates and have done 5 -25+ gallon water changes 5 weeks in a row time for next action. Upon advice from several sources I am ...

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ok the newst critters in my tank were a Derasa Clam and a yellow face sleeper goby. My tank is only two months old so still building up my cleaner crew. For two days the goby was doing an amazing job sifting sand and building his nest. last night as he was spraying his sand and he sprayed over the clam depositing sand into the clam. A bit later he decided to go clean up his mess and attempted dive into the clam and get the sand. FYi this clam is 6 inches wide, the clam snapped closed and just missed ...

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OK reaching out to smarter people. My tank is now two months old and yes I may have added some corals at 4 weeks which is too fast. My tests at that time showed 5 or less nitrates so figured i was cool. i got this set up used with all the rock and sand and even moved about 40 gallons of the original water. I never really got the ammonia spike or the brown algae but I have lots of green algae now. I figured since I moved so much stuff that I may have skipped that stage. i test for ammonia Nitrates, ...