The 55 gallon.

[Rocksor]

Water has gotten harder in the tank, 8.4. Any advice on how to lower it? (My tank contains a lot of limestone and a chunk of dead coral)

That's a measure of ph and not hardness GH

[The Cichlid Keeper]

Well, I could say I'm new to the Melanochromis- and I didn't know which ones were overly aggressive at the time. I didn't think Auratus were actually that aggressive! Now I know.
Yellow Lab is doing fine- Making me think he's a male Kenyi because I occasionally see him attack the Mainganos/male Johaniis! Overall plan based on keeping these fish is I think I'll keep this mysterious fish until its become likely that the Auratus will kill the lab, ten AUratus, 5 Mainganos, 5 Red Zebras. I honestly think these all have about the same level of aggression so they'll be too distracted to target the solo Lab. Have a Right size C Penguin Marineland filter and am planning to get one of them Marineland Emperor filters. The fish are all about 1.5 inches or bigger- possible exception of the lab. The Loach and Pleco are UTTERLY ignored.
Current Stocking: Three M. cyeanorhabdos, Three M. Auratus, 1 Yellow Cichlid, 1 Albino Bristlenose Pleco, 1 Black Kuhli Loach. I think I'm good to go as the aquarium is happy and I'm convinced the fish are happy right now too.