Overstocked tank - and limits for alkalinity

I have heavily overstocked 30 gallons tank with high
pH swings and low pH average (day: 8.1, night 7.6)
I was wondering if there is a way to help things up
a little without removing animals or moving to a bigger
tank... What are the safe upper limits of alkalinity?
Currently my alk is around 10-11'dK and still my pH
swings is low and swings too much. Enough to say I see
shells the hermit crabs live in dissolve in the water
causing my Ca levels to be above 500mg/l...

I was reading about alkalinity that high levels stabilize
pH in the upper levels but I do not see it happen in my tank.
How one can explain chemistry in my tank ?

"Pszemol" wrote in message
...

I was reading about alkalinity that high levels stabilize
pH in the upper levels but I do not see it happen in my tank.
How one can explain chemistry in my tank ?


Perhaps your room has an excess of CO2??
Can you open a window?
Sounds terribly simple but it worked for me.

Here is a must read:
Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm



--
Toni
http://www.cearbhaill.com/reef.htm