Welcome to Tropical Fish Keeping forum.
As nicolaas mentioned, knowing your source water GH (general hardness) and pH will help us point you in the best direction.
I will also mention our fish and plant profiles, second tab from the left in the blue bar across the top of the page. Each profile has data on preferred water parameters, along with numbers for shoaling fish (like tetra), tank size, etc.
As you've mentioned dwarf gourami, this is a fish I would avoid due to health risks. You can read more in our profile. Click the shaded name. If the common or scientific name used in the profile is types in a post, it will shade as a link to the profile.