Low pH issue ... looking for input...

[mccorry]

Hi everyone....

I noted a pH drop in my 125 Gal. reef tank a few weeks ago.  I've been watching it closely and trying various things to get it to come back up... with no luck.  Just got running my #'s this morning...

10:45 AM
Temp - 77.1 F
pH - 7.47 (will climb to 7.8-7.9 by the end of the day... but doesn't go much higher)  *via API drops and ReefKeeper pH probe
SG - 1.02575
Amm - 0
Nitrite - 0
Nitrate - 0.2
dKH - 9.45 (I dose for a target of 12 dKH)
CA - 375 (I dose for a target of 420 CA)
Mag - 1440

I've tried water changes along with buffering my tank up to 16-17 dKH with no success.  I've added fans to blow air over the top of the water surface for increase gas exchange.  I've upped my skimmer duty.

Anyone else ever see this?  Any ideas as to what I can do to get the pH back up to 8.0-8.2 range? 
Thanks for any input....

Steve

[lazylivin]

I know it is hard to not worry about what your PH is but you really shouldn't. Just dose alk and Calcium in your target range and your PH will be fine. DKH of 16-17 is extreme, consider keeping it at around 9-11. Are you dosing Sodium Bicarbonate or Sodium Carbonate?

If you determined to raise it here are some suggestions.

1.) Run a airline tubing from your skimmer outside. It will have to be fairly good size so it doesn't restrict airflow and affect skimmer performance.
2.) Dose Kalkwasser instead of Soda Ash
3.) Put a good size air pump outside running to an airstone in the sump. This is the one I ran for about 6 months. It worked to raise PH but I noticed no difference in corals so I removed it. https://www.petsolutions.com/C/Aquarium-Filter-Accessories/I/Super-Luft-Pump.aspx
4.) If you can open a window, not usually realistic this time a year
5.) Stop breathing so much, again not to realistic. This is the cause though. You are breathing in Oxygen and exhaling Co2. More people in the house the lower your PH will be.

[Wall_Tank]

I would validate that introducing fresh air brings up the ph.....then you can decide what to do.

When you say your Alk is at 9.45 and you are dosing target is 12.   Why are you so far from your target?

Another option for ph is to put some macro algae in the sump running on a reverse light cycle to your display.

[CoralBeauties]

What are you testing your ph with.  If it is a ph meter I would clean and recalibrate the probe.  what lazy and wall are suggesting is that your co2 levels might be high causing the drop in ph.  The best way to test for a higher co2 level is to test some fresh drawn water from the tank.  then run an air pump with an airstone in the water for several hours and retest.  If the ph level went up then it is a sign of higher levels of co2.  I experienced the same thing several years back and I did lazy's tip and ran my skimmer intake outside and was indeed able to raise my ph levels.
Jeff

[mccorry]

I've got a ReefKeeper.  I've cleaned the probe and recalibrated (2-point 10.01/7.00).  Also verified low pH with API drops (color indication).

I need to look into running the skimmer air line in from the outside.  Don't really have a good way to do this, based on where the tank sits and it's orientation in the room.
I did start dosing Kalk and using Kalk in the ATO tank.  pH is slowly coming back up.  Was 8.02 last evening when the lights went off....

[mccorry]

When you say your Alk is at 9.45 and you are dosing target is 12.   Why are you so far from your target?

Another option for ph is to put some macro algae in the sump running on a reverse light cycle to your display.

I have a reverse cycle light in the sump... but no Macro Algae right now... just some LR rubble.

I dose Ca and Alk every weekend.  I don't have metering pumps... so I dose manually.  dKH drifts from 12 --> ~9  over the week.  Ca typically goes from 420 --> 400
It's not consistend drift, so I've not moved to adding via the ATO system.

[CoralBeauties]

Try the bubble test on the tank water sample before you go to the trouble of running the skimmer airlines outside.
Jeff

[Wall_Tank]

I have a reverse cycle light in the sump... but no Macro Algae right now... just some LR rubble.

I dose Ca and Alk every weekend.  I don't have metering pumps... so I dose manually.  dKH drifts from 12 --> ~9  over the week.  Ca typically goes from 420 --> 400
It's not consistend drift, so I've not moved to adding via the ATO system.

A swing of a dKH of 3 over the week is too much for most coral.   Not so much the swing down, but when you dose to get back to 12, that is a huge swing.  That is leading to your large fluctuations in CA/Alk dose rates as the health of the corals change.   You should dose more frequently,  that will help stability everywhere.

[Steve]

I always have low PH in the summer and winter when the windows are closed. High in the spring and fall when the windows are open. As long as the alk, cal and mag are stable I never have noticed any ill effects on the coral. I agree with Wall-Tank that the 3 point swing is not good. I would look into daily or at least every other day dosing.

[mccorry]

I'll try to dose moreoften.  the issue is that the consumption is not steady....

[Wall_Tank]

The consumption will stabilize once you stabilize the Alk swings.

[mccorry]

OK.... thanks.