Reducing GH with Water Softener

[farne230]

I live in limestone country where our public water system derives its' water from the Edwards Aquifer, very hard (GH 300ppm, dh 16.8 / KH 300ppm, dh 16.8). My pond water chemistry is (GH 175ppm to 230ppm or dH9.8 to dH 12 / KH 107.9ppm or dH 6). I have tategoi gosanke with potential and I want the beni to and skiroji to develop to their potential, no shimies or fading hi. What do you recommend. Pond volume is 8,300 gallons, concrete and polyurea lined pond. I do one 1,000 gallon water change per week, turn over rate is approximately every 30min to 40min and I use 200kg of bakki house media on two returns and 9.0 cu-ft bead filter with alpha one media and UV light. I do have small vortex prefilters before the bakki showers. Pond will be heated within a few weeks. Also one bottom drain with air using 80L of air, clean bottom and small water fall (see photo).

I would like to reduce GH with a water softener. DO/RO unit may be too wasteful and costly to reduce KH too. Looking for your recommendations?
Bob