Ph Dropping??
 

My parameters have been very good since starting this tank. Everything normal/zero and pH usually at 8.2. Ca is at 420 and KH at 10. My pH has recently dropped to 7.8(measured at the end of the day as always). Was 8.0 about 2 weeks ago so I think it may be a trend? Concerning??? Should I be changing something or adding something?
Inhabitants appear normal. Perhaps 1 or 2 less "perky" corals but nothing that really looks off. I recently attempted fragging some overgrown Anthelia that didn't go all that well - could just be the cause of less "perky" corals.
Any suggestions?

ph test expired??

No, it's only 4 months old.

do you use kalkwasser

No additives yet, as all Ca and KH levels have been normal so far.

i see you test at the end of the day, just after lights out or have your lights been out for a while?
as co2 increases at night ph lowers, also whens the last time you did a big water change? the more waste build up in the tank will lower your ph.

Do you have a sump? If not are you using some type of surface skimmer?

Tanks without sumps can sometimes have a film buildup on the surface of the water that inhibits co2/oxygen exchange which can lower ph.
Even if you do have a sump try pointing a powerhead directly at the surface see if that helps to raise the ph at all

Well it is time for a WC and I did that this morning so hopefully that will help. I will retest pH tonight. I always test right at lights out. Also I added another powerhead and pointed one at surface for more agitation.
Thanks for the tips - hopefully this will fix it! Oh and no I don't have a sump nor a surface skimmer.

Are you using a glass cover? If so, that could be preventing the excess co2 in the water from gassing off.

No just eggcrate cover, but thanks. Hopefully I just need to angle the powerheads up more.