Are you certain of the composition of the precipitate?
Do you pre-rinse your bricks, and what brand are they?
You can build a solar desalination kit that could provide you with a cleaner water source; they use solar desal on a large scale in Israel but with some ingenuity you could build a small one with a pump, reservoir, evaporation area (2L soda bottles?) and condenser. Or catch the water off your ac or dehumidifier. It's distilled; just make sure it doesn't have metals dissolved in it.

Try switching to a hydro-organic nute like Canna that buffers in a good range already and isn't composed of chemical salts that are likely to recombine.

Look into humic acid sold as 'Soil Syrup' and other trade names, which also prevents recombination of fert salts.

Switch to a fertilzer formulated for hard water. They do exist.

Nice to see you again.