Wash routine with hard water?

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I am cloth diapering my twins. Currently they’re 5 months old (3 months adjusted) and I’m washing about 16 diapers every other day. (That could be off as I haven’t counted ) I just discovered that we have hard water and I’m afraid it’s effecting how clean the diapers are getting. What can I do to fix this? Also is it ok for me to be washing 16 diapers at once together? Could that also effect how well they’re being cleaned? I currently use ALL FREE AND CLEAR detergent. Any advice is welcome!