Chevrolet: fresh water coolant instead of anti-freeze, water coolant, fish tank

Question
96 chev silverado 5.7 vortec 180k

I put about 1/2 gal RV-Marine fresh-water coolant in the reservoir.  Will it hurt anything ?

Motor already has anti-freeze (D*oh on my part) and has not cycled reservoir contents yet.

thanks for your help

Jennifer

Answer
I HAVE A 99 SILERADO AND I PUT NOTHING BUT ANTIFREEZE AND TAP WATER IN IT. WHAT IS MARINE FRESH WATER IS THAT FOR A FISH TANK ? IF SO YOU ARE OK BUT IF YOU LIVE IN A COLD AREA DO NOT BE ADDING WATER FROM NOW ON ADD ANTIFREEZE OK . AS LONG ASD THAT WATER IS FREE OF CHEMICALS YOU WILL BE FINE BUT AGAIN ADD ANTIFREEZE FROM NOW ON AND WHEN YOU ADD A LITTLE TO THE RESERVOIR  USA A MIX OF 1/2 WATER AND 1/2 ANTIFREEZE FROM NOW ON. AND DURING THE WINTER USE ANTIFREESE  AND USE A GAUGE TO TEST ITS FREEZING RATE. AT WHAT TEMP IT WILL FREEZE OK YOU SHOULD BE JUST FINE - AND REMEMBER USE GOOD OIL AS THAT CHEEP OIL IS ONLY GOING TO HURT THAT MOTOR OK.
BIGW45