i have a 75 gallon tank that had a bad ammonia spike what can i do to get rid of it i am currently draining it completely and going to clean it out, get new filter systems etc. it used to be a saltwater tank but i scrubbed it good and it used to be a good balanced tank but it just suddenly did this also whaat kind of south american cichlids could i keep in this i was wanting to have a community but any other fish stocking suggestions would be appreciated thanks