Have had a 10 gallon for years and want to go bigger. A 20 gallon fits the space and budget. A larger bow front would be ideal but pushing it on the space we have. Anyways I'm here to ask for recommendations on piecing one together vs a all in one kit. If piecing one together what specific items should I look for as far as pump, filter, substrate ect. Any all in one kits that are good?