nitrates are harmless. Don't worry about it. In fact in planted tanks
people try to get more nitrates which the aquatic plants need to live. I
would agree with those that say as long as they don't go off the scale it
will be fine. As long as you are doing your weekly water changes, don't
worry about it.

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Margolis
http://web.archive.org/web/200302152...qs/AGQ2FAQ.htm
http://www.unrealtower.org/faq