Novaqua, if kept in moderate temps, will be good for about 5 years. So a 16 oz container should be a decent size for that period of time with a small tank like that. Of course, you'll need not to switch water conditioners during that time to get your moneys worth. Then again, I can see more, larger tanks in your future
Product sheet for Novaqua if you're interested: http://www.petsforum.com/novalek/kpd41.htm
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