Thank you for you reply. Please excuse my ignorance about these things
but I have no idea how to get this information. Is a water testing kit
that can be purchased that will give all this information? I live in
Jakarta and I dont know how advanced they are with these things. The
tank is 60 litres, has quite a bit of rock in it with a filtering
system consisting of an external motor, a unit that appears to pump air
through a tube into a plastic cylinder with a ball in bottom that
generates air bubbles into the water. I assume this is a filter. The
tank walls are cleaned daily. I clean the filter unit about once a
fortnight, usually as soon as I see it getting dirty. The water is part
changed about once a month although over Christmas it went about two
months because there was no suitable water. I use two lights. A purple
and a flourescent.
The tank seems to be clean and bright and the fish pretty energetic. I
have two anenomes, a coral and three pipe plants. These are all very
healthy. Sometimes I have trouble with red algae and have to take the
rocks out and clean them.

Thank you for your help.
Nicodemus