rusty color on plants

Question
We have had our 10 gallon aquarium set up since December.  We have lost a few fish.  You said we probably put too many fish in it too soon.  We now have 8 fish.  Our only problem now is that there is getting to be a rusty color forming on the plants.  We had the water tested about a month ago and were told that everything was OK, but the nitrate level was a little high.  We have been cleaning and changing the water every 3-4 weeks and we change the filter cartridge every month.  The fish seem OK as of now.  Can you please tell me what causes the rusty color?
Thanks

Answer
Hi Dana;

This is just algae. Brown algae is common in new tanks. You might try changing water more frequently. Smaller changes more frequently are easier on the fish anyway. Remove 25% of it every week to two weeks. It will help cut down on the "fertilizer" (dissoved fish waste) that makes the algae grow. It's best if you don't change the filter at the same time you do a water change. I try to change the filter a week before or after I clean the tank. It preserves the beneficial bacteria in one or the other area (filter or tank) so you don't get elevated toxins afterwards.

You can join us on the freshwater fish forum at About.com to get even more information too;
http://forums.about.com/ab-freshaquaria/start

There is a wealth of information there. My member name is ChrisR62. See You There!

Followups welcome

At Your Service;
Chris Robbins