You can easily adjust the hardness with Reverse Osmosis water, in lessening the mineral content by dilution.
You also can use all RO or RO/DI Reverse Osmosis/Deionization which can be found for sale at most SW fish stores for ~$.50 per gallon. Using one similar to this, as long as it is rated for drinking water.
https://www.bigalspets.com/seachem-...31xB8_MlujzRXxzZ5AonktDLkExLLR7RoC5eoQAvD_BwE
Or buy a small RO system, might be more economical to select fish which thrive in your water type. You need to see what the numbers are when you get the chance for your water.
Often fish on the borderline of ideal parameters, often can adapt to very similar parameters. Occasionally a fish must have a certain type of water, those usually have that notation with their care information so with a few checks you can see if it will match up alright or not.
When you start making up an actual list of possible fish, armed with the water parameters of your tap, you can compare which fish are the most favorite you have.
Then see how many others cross match in compatibility, and availability in stores around you or if you can get them shipped to you from a seller.
Although social distancing is in effect check out if there are any clubs or Aquarium Society groups meeting around your home zone. Local resources /other hobbyists are often great because they may have been raised in the same type water you have.
Building a new tank is FUN!
