Reef pH range

[rock_lobster]

My pH is so unstable. Every day it goes from 7.56 at night to 8.2 during the day. Alkalinity is stable at 8 and all inhabits seem to be doin fine. Is this normal or should it be something I need to correct?

 

[Newb73]

I run a Kessil 150 in my sump on reverse schedule, dos 2 part with the alk going in small doses every 15 minutes over night, run an extra main pump at night to increase gas exchange (with the wave makers in the tank reduced) and run a C02 scrubber attached to the intake of my skimmer. My ph goes to about 8.1 at night and 8.3 in the day time with my alk around 9. If I'm running gas logs like I am right now it goes down to about 8.05 at night and gets to about 8.22 during the day.

Before you start taking any action recalibrate your PH probe just to be sure. I would just do one thing at a time....starting with a refugium light if you don't already have one and go from there. Although the cheapest thing (others will disagree) is the C02 scrubber...its a $50 2 little fishes media reactor and a 5 gallone bulk bucket of veterinary grade filter media for about $80 bucks which from what I am seeing...will probably last me a couple years.

Another cheap thing is just to look at your circulation. IMO tanks with more circulation than need and oversized skimmers help being the improved gas exchange leads to a more stable PH. This is one area the gyre really shines with its immence surface agitation

 

[Downbeach]

Here's a good read:

http://reefkeeping.com/issues/2007-05/rhf/index.php#6

Since its the CO2 in your system that is driving the pH, a good working skimmer will go a long way in helping your system reach equilibrium with the surrounding atmosphere through gas exchange. But, if the surrounding atmosphere has high levels of CO2, as it does any time of year you have to close the house up due to weather, then your pH will reflect that condition, i.e. higher CO2 = lower pH. One of the easiest, least expensive methods to overcome this issue is to bring in outside air by using a 1/2" tube run from your skimmer's intake to an outside air source with much lower levels of CO2, if practicable. Another method is to add a refugium with some macro algae, which will take up some of the CO2. The use of kalkwasser(pickling lime) in your top off water will also utilize some of the CO2. I have used a CO2 scrubber, and they do work, but, the media (soda lime) can get expensive. The use of any/all of these methods will not change the fact that there is a diurnal change in pH. All these methods have their own set of idiosyncrasies, so do some research on the one(s) you might want to deploy. I also agree with newb that a properly calibrated device is important if you want an accurate reading.

 

[Randy Holmes-Farley Verified Community Expert]

My pH is so unstable. Every day it goes from 7.56 at night to 8.2 during the day. Alkalinity is stable at 8 and all inhabits seem to be doin fine. Is this normal or should it be something I need to correct?

I'd try to raise that low end, if it is accurate. There are many ways to get rid of the excess CO2, as noted above, possibly including just more aeration, depending on the CO2 in your home air.

 

[rock_lobster]

Thanks for the reply! I guess my first question should be: is this potentially a problem and the second steps to remedy it. I have a small tank 20 gallons and very limited space. I run a Refugium with 24 hour lightning and no skimmer. I do water changes weekly about 8%. ORP is usually around 400. There is no room to add a skimmer in the rear compartment.

 

[rock_lobster]

Really doesnt make much sense. I have little to no algae in the display so when the lights go of there why does the pH tank? there is tons and tons of algae in my refugium on 24 hour lighting.

 

[Randy Holmes-Farley Verified Community Expert]

pH 7.56 is a problem, if real. It is low enough for coral skeletons to very slowly begin to dissolve. I consider pH 7.8 to be a reasonable cutoff between not concerned and concerned about low pH.

The lights are probably brighter in your main tank, but even if not, the main tank will produce CO2 at night, lowering pH relative to the daytime, even with a 24/7 refugium.

 

[rock_lobster]

Thanks! Okay I'm sure the result is correct I have 2 pH probes reading nearly the same range and they are both relatively new. The tank has fairly good aeration so I'm guessing it may be whole house CO2 that is causing the issue (I live in a small condo). Is there any way to make a whole house CO2 scrubber?

 

[Randy Holmes-Farley Verified Community Expert]

Thanks! Okay I'm sure the result is correct I have 2 pH probes reading nearly the same range and they are both relatively new. The tank has fairly good aeration so I'm guessing it may be whole house CO2 that is causing the issue (I live in a small condo). Is there any way to make a whole house CO2 scrubber?

They might both be calibrated wtih the same off fluid, but it might be real.

To test if it is aeration you need or less CO2 in your home air, try the aeration tests described in the article linked earlier, using inside and outside air.

The fact the the pH swing is pretty large suggests it is at least partly inadequate aeration, but the test will clarify.

 

[rock_lobster]

Today I performed half of the aeration test. Taking water out of the tank and aerating it this morning immediately brought the pH up from 7.6 to 7.9 but it has leveled off at 7.9 which is interesting. Seems there is both a component of low flow and high indoor CO2 that are causing the issue.



Ah I should have tried the test before opening the windows and running the AC fan its been going for about 6 hours now so I imagine the CO2 if it were concentrated inside has already cleared. Currently I've got the windows open and a pump blowing accross the top of the water for additional circulation havent noticed much increase yet its currently at 7.8 which is the same

They might both be calibrated wtih the same off fluid, but it might be real.

To test if it is aeration you need or less CO2 in your home air, try the aeration tests described in the article linked earlier, using inside and outside air.

The fact the the pH swing is pretty large suggests it is at least partly inadequate aeration, but the test will clarify.

 

[Randy Holmes-Farley Verified Community Expert]

Do you have a skimmer?

 

[surfnsalt]

pH 7.56 is a problem, if real. It is low enough for coral skeletons to very slowly begin to dissolve. I consider pH 7.8 to be a reasonable cutoff between not concerned and concerned about low pH.

The lights are probably brighter in your main tank, but even if not, the main tank will produce CO2 at night, lowering pH relative to the daytime, even with a 24/7 refugium.

Sorry not trying to jack a tread but my 14g in my bedroom runs a ph of 7.8 to 8.2 everyday. Is this swing of any concern for a sps tank. I just started running a skimmer at night only but didn't see much difference. I'm sure the co is high this time of year especially we sleep.

 

[Randy Holmes-Farley Verified Community Expert]

Sorry not trying to jack a tread but my 14g in my bedroom runs a ph of 7.8 to 8.2 everyday. Is this swing of any concern for a sps tank. I just started running a skimmer at night only but didn't see much difference. I'm sure the co is high this time of year especially we sleep.

No, that is not a concern. :)

 

[rock_lobster]

No I don't have a skimmer. I've been using the back compartment as a refugium with a strip LED laying over the top of it full of chaeto. The algae has been growing fast. It seems to me that circulation is large part of it. My rear pumps were a bit dirty so I cleaned them and the flow boosted a lot. pH is up higher now and I aimed the koralia up to the surface to aerate the water more. So hopefully with these measures it doesnt drop below 7.8 tonight. Also decided to purchase an jebao RW4 to try out for a more natural flow.

Do you have a skimmer?

 

[Randy Holmes-Farley Verified Community Expert]

OK, sounds good.

Happy Reefing. :)

 

[rock_lobster]

Been a while now and the pH is looking much better between 7.8-8.2. Ive started leaving the windows open as much as possible and that seems to have resolved the problem. Kept flow the same with a little more surface agitation. Seems the main issue was indoor CO2. Also, I put candles out as soon as my girlfriend lights them lol.

 

[Adamwheel]

I had a similar situation and recently solved it for good.

I drilled a big hole in the side of my house near ground level and then ran 3/8" ID hose to my skimmer intake.

Ph seems unaffected now when the room is full of people or empty.

It's a great feeling to no longer chase Ph.

Good luck,
Adam

Reverse photo period on Refugium helps very little for me.