Check your meter and calibrate it again. If, as I imagine, you have done
that then there is the possibility that you need a water change. If that is
already done consider adding a pH riser. If that is not convenient at this
time something is lowering your pH, food? supplements? medications? heat?
poor circulation? testing kit?
there are many possibilities...
iy
wrote in message
...

Hello;


I've got a 210 gallon reef tank with a PH running between 7.8 -8.0.
The
alkalinity is near the top, around 3.0 or so. Any parameters I should be
looking at that could affect this? Everything seems to be doing pretty
good and
that includes fish
(Naso, Purple, Sailfin, Clown, Hippo tangs & foxface which are on the
large
side, 5-9 inches, a madarin dragonet and 4 gobies (2 fire, dragon and
diamond.)
Corals are 4 clams and mostly softer corals such as leathers, colt,
mushrooms, hammer, cups, pagodas, finger, foxglove, etc....

the tank has a deep sand bed and probably 225 pounds of very mature
live
rock with alot of coraline algea
55 gallon sump
mag 24 & mag 12 main pumps (about 3000 gph circulation)
Aqua C 180 protein skimmer
3 mag 12 pumps for internal circulation
750w 10k MH
960w VHO

nitrite, nitrate, ammonia and phosphate seem fine

I use an aquacontroller jr for temperature control (among other
things)
and tank stays at a constant 80 degrees.

It was running between 8.1 and 8.3 and can't figure out why the dip.
Any
sugestion welcome



thanks

Bob