I'm gonna do something little out of the box, I'm a little uncomfortable doing this but for my hard tap water I'm gonna go for it but at half the recommended doses. Langbeinite. Cool cat named Kratos (from Rollitup) informed me the following..
"Unfortunately, the source of your water's alkalinity is the CaCO3. Attempting to pH your tap water will prove fruitless and a waste of time, resources, and not to mention the frustration.
Your soil will never be able to 'buffer' water. Soil buffers (like lime) only serve to buffer the soil. The water is a component. Buffering water and pHing water is something that is only for RO water, because RO water is stripped of everything.
Do a side-by-side grow in pots, with literally any plant. One soil with dolomite lime, one soil without lime. Use your tap water source on both. Over time, you'll note that the soil without langbeinite struggles, and the one with langbeinite flourishes.
Unfortunately, unless you get RO water, you'll need to have a constant supply of Langbeinite for any container growth. If you can plant in the ground outdoors, you'll have no issues.
This is because the water will flow down below your root zone, and any crystalizing of the CaCO3 will occur far below the root zone and, as a result, not have a negative impact on your plants."
This could go South..or it could go OUTSTANDING... (Am I using Kratos as a scapegoat? Of course I am!

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half cup of Langbeinite per pot.. stay tuned