Im pretty sure your referring to Diatoms, they feed from Silicate present in
the water...

Test your tank and the water you use (for changes) for Silicates present...
if you use a good RODI water it should be free from Silicates otherwise you
are just replacing the algaes food source every time you do a waterchange!

In my new tanks i just leave the lights on with rock and pumps and skimmer..
No livestock or corals and let it kill itself by growing all over and it
then uses up its food source and dies...

Something like that anyway

W


"Mooboy" wrote in message ...
OK i love my newdual 250watt 20k metal halide setup on my reef tank but
the
brown algae that grew with my pc's grow ten times faster now.How to i
limit
its production?more snails????
Thanks