Water carbonate hardness

[GabeC]

Hello
I bought a 180l freshwater tank about 10 weeks ago which I change 30% each week. I have it planted and have about 20 small fish mainly tetra and mollies.
However when I do weekly tests my water is always carbonate hard and I am not quite sure how to fix this. My fish shop told me to use my spare utility tap water and not to my house water as I run this through a salt tablet system to soften it but the result is as suspected High and Hard Carbonate.
My question is, is it really unsafe to use my treated water or do I use other chemicals.
Thank you in advance

 

[King Fisher]

Are you having trouble with your fish or plants?

 

[GabeC]

Are you having trouble with your fish or plants?

Thank you for the response.
No the fish seem happy enough and although the plants are OK some of them have a lot of dark green algae on them which I’m treating with seachem flourish excel which I am hoping will help.
Any ideas or help would be appreciated.
Thank you.
Gabe

 

[ZxC]

I run mine through a softener and remineralize with my own chemicals, but as you have access to pre-softened water just use a 50/50 mix and see where that lands you. Most aim for 3-6 degrees of carbonate hardness. Oh, mollies prefer harder water if I remember correctly

 

[GabeC]

I run mine through a softener and remineralize with my own chemicals, but as you have access to pre-softened water just use a 50/50 mix and see where that lands you. Most aim for 3-6 degrees of carbonate hardness. Oh, mollies prefer harder water if I remember correctly

Thank you for your suggestion - I guess using my softened water with my weekly 30% water change next week will do no harm. I’ll let you guys know what happens.

 

[King Fisher]

Those fish will be fine in hard water. I'm not totally up to speed on different plants but if they seem to do fine with the hardness I'd keep it that way.

 

[GabeC]

Those fish will be fine in hard water. I'm not totally up to speed on different plants but if they seem to do fine with the hardness I'd keep it that way.

Thanks again for your concern.
Gabe