What causes ph to go down

I have been using a 8.3 buffer and it seems as if the ph after one night goes down to 7.8 to 8.1.
I found that at 8.3 to 8.5 my tank looks great, but constantly adding buffer seems the wrong approach. So what are the causes of ph to lower?

Maybe I can trace the problem and solve the problem.

 

Improper alk, mg, ca balance
low oxygen (both in tank and in room)

Also, make sure you are testing the PH at the same time, every time.

 

excess of CO2 molecules in the system is one cause of low PH
to check if that is the issue , take a cup of water out when your PH is reading low,
add an airpump air stone conbination to it and test again in 1 hour. If the PH is now higher, it means there was an excess of co2 in your water and that drove the PH down

if thats the case, more surface movement will help gas exchange
also if you have a sump, reversing the lighting will help, as that would mean your fuge or Macro algaes in it would be producing Oxygen when the DT lights where off thus helping to keep PH more constant over 24 hours

Steve

 

:thumb_up: that solved my fluctuating pH problem when I was new

 

Ok I just reprogrammed my fuge light to turn on after main tank lights out, and turn off before MH turn on.
I also just hooked up an air pump and Ill pick up an air stone tomorrow. Should I put the air stone in the main tank or in the fuge?

Im already testing the same time of day.

 

Sounds good. You can stick the air stone wherever, it wont matter. I run mine in the sump.

 

no need to put air stone in the tank or fuge
just use it for the experiment to find out if CO2 is the root cause

take a cup of water when your PH is at lowest so at night is good - pump air into that cup of water
1 hour later test the PH of the cup of water and if its more than it was when you 1st tested it, you will know CO2 in the tank is what caused the PH drop

reversing the light cycle on the sump will probably have the desired effect, but angling some P heads or returns to move water surface more will also help the CO2 escape the tank

also if you have a tight fitting cover to prevent fish escape then you may want to create some gaps in that to help further with gas escape.

airstones in reef tanks can cause issues - bubbles burst causing salt to be deposited on stuff above like light fixtures etc

Steve

 

To biggy back on what Steve said, after you take the glass of water and do the air pump/air stones and test for PH thing, take that same glass of tank water and do the same outside. Then test again and post your results.

Luna

 

O2, dKH imbalance

 

Shouldn't my skimmer be performing the same action an airstone would perform?