I can't seem to find the posting that I received in an email so I will see if I can help anyway.  I believe that the small red worms are not harmful and only live in healthy systems.  We see them sometimes too.  Sometimes it seems that we need to top off our tanks more often than others.  Sometimes its because we have a leak somewhere and we just weren't able to find it early enough.  Our system is pretty large with lots of potential places to loose water.  Other days it just seems like the plants took up more.  The part about the fish is puzzling if all your levels are good.  What is your water temp?  Are you using a dechlorinator when you add water?  Do you have enough air stones?

Leisa