Take them back, firstly the water temperature needs to be between 28-32 oC and the PH between 5-6. Also the GH needs to be between 0-12DGH.
Most of the fish in your tank wont be able to handle the temperature, keeping Mikrogeophagus in the wrong parameters can lead to slow immune response, slow digestion and hexamita, which is pretty common when these conditions aren't met.