How can I lower the ppm of the water in a cost-effective way? My tap water comes out with 375 ppm, which is way too high for me. It's probably a lot of lime in the water.
Filtration. I would just cabon Filter it. I use one on my indoor garden hose for them. Was about 35 bucks. Will remove chlorine and negative stuff in water. I would not worry too much about the ppm after that. Plant can likely use anything left over. I am guessing you are on well water. So lime and calcium are likely heavy in water.
The only way to do that would be to mix it with some distilled water or RO water... I'd probably mix 1 part tap water with 2 parts distilled to cut that ppm down to about 125...
Good luck!