Your Calcium level is very low. It should be within the range of natural
sea water which is 400-450ppm. You could stand to raise your KH, too.
Between 8-11dKH is good.

-Todd

"Marx" wrote in message
...
Marc Levenson wrote:

Marx, you don't have too much light at all. 150w of light 10" off the
water of
a 30g is weak, actually. I've got 165w of PC lighting over my 29g.

Coralline can fade to white but later bounce back. Perhaps your water
parameters are a tad off, so I'd recommend you test pH, Calcium and
Alkalinity
to see where those numbers are.

PH 8,25
KH 7dKH
Ca 300ppm
Mg 1000ppm

Those numbers are from memory, i'd note them at home, and will correct
if needed.
I'm dosing kalkwasser daily as top-off water.
I'm trying dosing MgSo4 as Mg supplement.
It's rather new tank.
I made DSB based on silica sand, but it caused algae bloom (cyano I
think) so i got it off.
Recently i added superactinic fluorescent Philips TL/03 20W, and bought
coraline sand to put instead of silica.
The last thing i suppose can cause problems is dual-ended MH, which is
known to not have shielding (my lamp have simple glass, not special).
I'm goig to hang today special AquaMedic glass as additional filter to
lower UV.
Marx