Low pH

ihavecrabs · Jun 17, 2016

Over the last few weeks I have head a dropping pH problem. Previously, my pH was between 8.10 - 8.30 and now it floats between 7.80-8.20.

My ATO water sits at 8.80 pH yet my tank swings are much lower. I do run a reverse light cycle and I have a lot of water surface agitation, a skimmer pulling air, and an air pump pulling air. More details below about my system.

I have checked pH with Apex Lab Grade (and yes it was properly calibrated) and a secondary check with a hand held pH unit. Both units read the same amount.

What can I do to assist in raising pH without impacting dKH? Do I need to raise it pH or am I OK as it is?

Setup Description:
Displays/Water Volume: 120g 4'x2'x2' with 20g sump and 60g secondary display.
Skimmer: EShopps S-120 skimmer (a little underpowered for my tanks
Lights: 6 bulb ATI over the 120 and a 6 bulb Tek over the 60g on reverse light schedule
120g on a 5pm off at 4am
60g on at 6am off at 5pm
Flow: 2x MP40 and 1x RW8 in the 120g and RW4 and MP10 in the 60g. Vectra M1 return.
Other Equip: 2x heaters, Apex, Air pump which used to power ATS but not just pumps air into tank for air exchange.

Parameters:

Temp - 78.4 to 78.8
Calc - 420
Alk - 8.5-9
Magnesium - 1480

Recent changes:

I'm beginning to dismantle the 60g and will be setting up a 20g high with coral and algae for reverse light schedule. As part of this, I have removed about 50% of the coral (sold) and moved the following fish to the 120. Midas Blenny, Mandarin Dragonet, 2 clownfish.
AC has gone on in my home about a month back. Note there has been no change in pH for my ATO water which is at 8.80.

Thanks all!!!!

ihavecrabs · Jun 17, 2016

@Randy Holmes-Farley

Downbeach · Jun 17, 2016

I ran a predominant SPS mixed reef for many years between those numbers, so I wouldn't worry about it.

GMay · Jun 17, 2016

You may have higher CO2 in the room as one possibility. Even with that, I do not think your pH is an issue unless it drops below 7.7 - 7.8. Many systems will have pH swings of this magnitude and are functioning just fine. Watch your critters, they will tell you you need to worry.

ihavecrabs · Jun 17, 2016

Downbeach said:
I ran a predominant SPS mixed reef for many years between those numbers, so I wouldn't worry about it.

Thanks, everyone looks happy so far. Just want to make sure!

GMay said:
You may have higher CO2 in the room as one possibility. Even with that, I do not think your pH is an issue unless it drops below 7.7 - 7.8. Many systems will have pH swings of this magnitude and are functioning just fine. Watch your critters, they will tell you you need to worry.

I thought that originally; however, my ATO reservoir is in the same room which a much higher pH. That initially ruled it out for me, excluding the possibility that O2 is potentially used up much faster in my displays and is not being exchanged effectively enough. Hard to believe with the surface agitation but still a possibility I suppose.

Happy to say, all critters are happy and healthy. SPS are growing and coloration is great.

Randy Holmes-Farley · Jun 17, 2016

IMO, that pH is OK, but to raise it will generally involve lowering the CO2 in the water.

ihavecrabs · Jun 17, 2016

Randy Holmes-Farley said:
IMO, that pH is OK, but to raise it will generally involve lowering the CO2 in the water.

Thanks. Any suggestions on ways to do so? Get another powerhead pushing water at the surface?

Randy Holmes-Farley · Jun 17, 2016

No, the CO2 is most likely from your home air. There are many options, such as open windows, an air line from outside to a skimmer inlet, limewater, growing macroalgae, etc.

ihavecrabs · Jun 17, 2016

Randy Holmes-Farley said:
No, the CO2 is most likely from your home air. There are many options, such as open windows, an air line from outside to a skimmer inlet, limewater, growing macroalgae, etc.

If it was the home air, would my ATO also be low too? Or because nothing is consuming the oxygen in the ATO, it wouldn't budge much?

Randy Holmes-Farley · Jun 17, 2016

ihavecrabs said:
If it was the home air, would my ATO also be low too? Or because nothing is consuming the oxygen in the ATO, it wouldn't budge much?

ATO, automatic top off?

ihavecrabs · Jun 17, 2016

Yes sorry, auto top off reservoir

Randy Holmes-Farley · Jun 18, 2016

I'm not understanding what that has to do with O2 or CO2. It won't noticeably impact either in the tank.

ihavecrabs · Jun 18, 2016

Since my tank and the ATO reservoir are in the same room, if the air has a lot of CO2 I would expect both the tank and the reservoir to be impacted. Is my assumption correct?

My reservoir is around 8.8 where the tank is considerably lower.

Randy Holmes-Farley · Jun 20, 2016

ihavecrabs said:
Since my tank and the ATO reservoir are in the same room, if the air has a lot of CO2 I would expect both the tank and the reservoir to be impacted. Is my assumption correct?

My reservoir is around 8.8 where the tank is considerably lower.

Yes and no.

Correct that CO2 gets into everything, but not that CO2 in pure top off water in contact with air is significant to a reef tank it is being added to.

ihavecrabs · Jun 20, 2016

Randy Holmes-Farley said:
Yes and no.

Correct that CO2 gets into everything, but not that CO2 in pure top off water in contact with air is significant to a reef tank it is being added to.

But in the assumption that the issue is high CO2 in my home air is causing low pH in the reef tank, the reservoir for ATO being high in pH in comparison should debunk that as the root cause of my issue.

So I should be search elsewhere for my cause of lower pH.

I agree, no concerns that the fresh water I'm using to top off my aquarium is linked at all to low pH.

jeremy.gosnell · Jun 20, 2016

Adding a CO2 reactor to your skimmer, is an option, however I doubt it will have the effect you're looking for. Your aquarium would have to be in a room with little ventilation and lots of people, for ambient CO2 to cause a ph drop. An easy test (if possible) is to run your skimmer's air-line out a window or door, so that it intakes fresh outdoor air. If you notice a rise in ph, you can conclude that ambient CO2 is your problem. More than likely, the corals (and other animals) within your system are using carbonate, causing a drop in ph. It can be confusing, because often you will test alkalinity and it is right where it should be, yet ph is falling. Randy could likely explain the mechanism that causes this better than I. When I've had this problem in the past, adding a kalkwasser reactor to my auto-top-off did the trick. Depending on your calcium/carbonate demand, a kalk reactor may take the place of two-part dosing. You will need to test dKH and calcium to make that determination. I would start with less than a 1/2 cup of kalk in the reactor, until you get a feel for the effect it has on water chemistry.

Randy Holmes-Farley · Jun 20, 2016

ihavecrabs said:
But in the assumption that the issue is high CO2 in my home air is causing low pH in the reef tank, the reservoir for ATO being high in pH in comparison should debunk that as the root cause of my issue.

So I should be search elsewhere for my cause of lower pH.

I agree, no concerns that the fresh water I'm using to top off my aquarium is linked at all to low pH.

The pH of purified water (with or without CO2) is not properly measured with a pH meter or kit, so the value you get is not reliable.

The way to check CO2 in the air, short of a meter, is to aerate a cup of tank water for an hour or so and measure the pH in that. You can do that with inside and outside air to check the effect of more fresh air in your home.