polyphosphate water softener ...

[scuba guy]

Any one use polyphosphate cyrstals to soften your Discus aquarium water?

I came across a carbon filter cartridge containing ployphosphate balls that slowly dissolve performing an ion exchange with calcium in hard water
(https://www.clarencewaterfilters.com.au/product/slow-dissolve-polyphosphate-scale-inhibitor-balls/). I want to know if this is safe to use in my discus aquarium.

I currently filter my incoming tap water with two large carbon blocks to remove chlorine. My incoming water is mildly hard and I would like to soften it. It's not practical for me to use reverse osmosis.

Thanks

[alron2]

Why do you want to soften your water?
Ron

[scuba guy]

I have moderately hard water that is precipitating calcium around the edges of the aquarium (glass top, etc.). It's not a problem for the Discus - they are acclimated to it, but I thought by slowly softening the water, the scale on my equipment will decrease and perhaps disappear altogether.