Dear Carol<br><br>The Brown Algae growing on the
rocks may be due to excess Silicic acid in your water.
Algae eaters will generally eat or remove only blue
green algae. Try using a reverse osmosis filter (your
aquarium or the local society will help you find one) or
write back to me and I will help you choose one. The
units a generally expensive. Try using activated carbon
in your aquarium filter or if you have a drinking
water filter system which includes chemical filter use
filter water. Try this and let me know the
results.<br><br><br> Brown Algae - Diatoms<br>Diatoms are single
celled algae, brownish in colour. It starts out as a
dustingOn the substrate that rapidly turns into a mat that
can cover the tank over in Just 5 days, provided that
they have a surplus on nutrients available.<br><br>The
cause: excess nutrients, silicate and silicic acid are
the ingredients for a diatom bloom. Silicic acid
enters the aquarium by using tap water;substrate can
contain silicates that leach out over time. RO/DI units
can filter silicic acid out, but only for a limited
time. Eliminating silicates can control
diatoms.<br><br>Regards<br><br>A.Shanta Manohar<br>Aquarist Society of
Karnataka<br>Bangalore<br>India