CORRECT CRAFT Nautique 220 Owner's Manual page 164

Care and Maintenance
A
CORC212
+ = red positive (A)
- = black negative (not shown)
To clean your battery, remove and wash down the battery case with
a diluted ammonia or baking soda/water solution to neutralize the
acid, then flush with fresh water. Keep the fill/vent caps tight so the
neutralizing solution does not get into the battery cells.
The electrolyte level should be checked every 30 days. Add only
distilled water to maintain the level between the top of the plates
and the bottom of the fill/vent cap. DO NOT overfill. Remember
batteries contain sulfuric acid which can cause severe burns.
8-9