Outside air for skimmer. Expected results?

[kilnakorr]

Pretty funny you say you dont know how it works then correct me lol. FYI when i mention oxygen it is related to the ratio of co2/oxygen levels in the air. So while technically high co2 is a depresser of ph introducing highly oxygenated air (ie less co2) drives ph up (assuming the tank has high co2 levels). And knowing the scenarios of when it works and why really is not that complicated. Even getting to the chemistry is not that complicated. As someone who knows very little about chemistry I manage to understand it.

Here is a good article. http://www.reefkeeping.com/issues/2004-09/rhf/

It's not the oxygen but lower concentration of CO2. Adding more oxygen will not lower ph, but adding less CO2 will.
The question is, does my skimmer add enough air to make a difference?

 

[mdb_talon]

It's not the oxygen but lower concentration of CO2. Adding more oxygen will not lower ph, but adding less CO2 will.
The question is, does my skimmer add enough air to make a difference?

In other words exactly what i said? Generally speaking if you have high co2 air you have less oxygen.

 

[kilnakorr]

In other words exactly what i said? Generally speaking if you have high co2 air you have less oxygen.

No. High CO2 does not mean low O2.
In this case, oxygen is irrelevant

 

[Gtinnel]

he problem with this test is outside temperature. Can't trust close to 0 degrees celsius water vs. 25 degree water.

Does pH fluctuate with large temperature changes?

 

[mdb_talon]

No. High CO2 does not mean low O2.
In this case, oxygen is irrelevant

Elevated co2 in homes almost always corresponds with decreased oxygen. Highly oxygenated air has less co2. Thus my statement earlier "So while technically high co2 is a depresser of ph introducing highly oxygenated air (ie less co2) drives ph up (assuming the tank has high co2 levels)". Again this really is not that complicated.

 

[ReefBeta]

In other words exactly what i said? Generally speaking if you have high co2 air you have less oxygen.

Well that's technically not true. Like air go through CO2 scrubber will have less CO2, but it won't have more oxygen. Not all reaction consume oxygen produce CO2, and vise versa.

 

[S.Pepper]

My PH went from 7.8 to 8.2-3 when I ran a airline from my skimmer to outside. YMMV

 

[ReefBeta]

I only have a few corals, so continously dosing anything will eventually put Ca or alk higher than wanted.

How so? If you continue dosing the among that's consumed, they will remain stable. With few coral, you just dosing less, but the manner of dosing is the same.

 

[kilnakorr]

introducing highly oxygenated air (ie less co2) drives ph up

highly oxygenated air does not mean less co2.
Introducing less air with less co2 concentration is what we try to achieve. Adding more oxygen does not lower co2 or raise ph.

 

[kilnakorr]

How so? If you continue dosing the among that's consumed, they will remain stable. With few coral, you just dosing less, but the manner of dosing is the same.

True. I've only measured a 0.05 drop in alk in a week. Not sure I can dose that little, and if it would have any effect.
I'm in progress of switching salt, so my alk should increase slowly with waterchanges which should also help in the long run.

 

[ca1ore]

Pretty funny you say you dont know how it works then correct me lol. FYI when i mention oxygen it is related to the ratio of co2/oxygen levels in the air. So while technically high co2 is a depresser of ph introducing highly oxygenated air (ie less co2) drives ph up (assuming the tank has high co2 levels). And knowing the scenarios of when it works and why really is not that complicated. Even getting to the chemistry is not that complicated. As someone who knows very little about chemistry I manage to understand it.

Here is a good article. http://www.reefkeeping.com/issues/2004-09/rhf/

Glad I could amuse you. I did not say that I did not understand how it works, just that it would be interesting to understand under what conditions external air is effective. I do not see the two as the same thing, though I suppose it is not unreasonable to conflate the two. For example, is a covered tank likely to benefit more from external air than an open top tank? Does having a basement sump help or hurt? Things like that. Although I have found just using external air to my skimmer to make essentially no difference, exchanging the air in my basement sump room can be quite helpful . Generally, though, I don't bother to chase pH anymore.

Not clear to me how the skimmer affects the balance though .... unless one is running one that is either significantly undersized or oversized. Frankly, I have always been skeptical of the amount of gas exchange that happens in skimmer anyhow.

Funny you link that article. I remember reading it back in 2004 .... long time ago though I suppose the chemistry hasn't changed.

 

[kilnakorr]

Does pH fluctuate with large temperature changes?

Yes. The below explanation seems logical:

pH is changed when temperature is increased because pH is a simplified way to numerically quantify the H+ ion concentration of a given solution. Increasing in temperature also increasing the molecular vibration of concentration of [H+] ion for this decrease tendency of forming hydrogen bonds, thus leading to reduction in pH.

 

[kilnakorr]

Not clear to me how the skimmer affects the balance though .... unless one is running one that is either significantly undersized or oversized. Frankly, I have always been skeptical of the amount of gas exchange that happens in skimmer anyhow.

Exactly. Skimmer adds air to the water and degasses CO2. But this exhange must be higher than the surface exhange. A large surface area in a room with high co2 concentration and small skimmer might not have any noticeable effect.

 

[mdb_talon]

just that it would be interesting to understand under what conditions external air is effective.

Again this is simple. The conditions it helps is if your tank has high co2 levels. Reducing them via outside air with less co2 can help....if the co2 levels are significantly different.

As for the skimmer it is very relevant based off how much aeration it is providing, but yes unless you are using an undersized skimmer to water volume it probably is not making a huge difference.

If you dont think skimmers provide significant gas exchange i just cant help you there.

 

[ca1ore]

If you dont think skimmers provide significant gas exchange i just cant help you there.

What, no 20 year old article to cite LOL .....

I'm all for perpetuating group-think, but is a skimmer really a significant form of gas exchange? I get that you cannot help, but perhaps somebody less dogmatic can offer a cogent argument. If a skimmer is sized properly, presumably the injected air is quickly 'coated' with proteins (the primary function of foam fractionation). I wonder if anyone has actually studied that. Hard to see how that then would be a material source of gas exchange. Just sayin' .......

 

[ReefGeezer]

FWIW, I don't ever check pH. Learned my lesson years ago. It is a parameter that will just get you in trouble if you start chasing it. It is just a function of the CO2 level in the room and the alkalinity in the water. I can't remember reading anywhere that there is a negative impact when pH is in the lower part of the range for salt water (7.6-ish) when alkalinity is maintained by hobbyists (7-11 dKh).

If I somehow decided to test pH and it was lower than desired, and I could raise alkalinity, I'd probably do so. Otherwise, as long as it was steady, I'd just let it ride.

 

[mdb_talon]

What, no 20 year old article to cite LOL .....

Is there something wrong with a 20 year old article that clearly shows how co2 impacts ph? Do you really think the chemistry has changed or do you just feel the need to be ignorant?

 

[mdb_talon]

FWIW, I don't ever check pH. Learned my lesson years ago. It is a parameter that will just get you in trouble if you start chasing it. It is just a function of the CO2 level in the room and the alkalinity in the water. I can't remember reading anywhere that there is a negative impact when pH is in the lower part of the range for salt water (7.6-ish) when alkalinity is maintained by hobbyists (7-11 dKh).

If I somehow decided to test pH and it was lower than desired, and I could raise alkalinity, I'd probably do so. Otherwise, as long as it was steady, I'd just let it ride.

It depends how you define negative impact. There is adequate research to show that calcification increases as ph increases. If the goal is faster growth then a depressed ph has a negative impact.

On the "chasing" ph i think that is one of those things easy to say if your ph is in an acceptable range. For people like me who have a low daily value of about 7.5(without taking action) then it is not so kuch about chasing a high number as it is to getting it into a reasonable range.

 

[ReefGeezer]

It depends how you define negative impact. There is adequate research to show that calcification increases as ph increases. If the goal is faster growth then a depressed ph has a negative impact.

On the "chasing" ph i think that is one of those things easy to say if your ph is in an acceptable range. For people like me who have a low daily value of about 7.5(without taking action) then it is not so kuch about chasing a high number as it is to getting it into a reasonable range.

Two questions (sorry if you already answered them): 1) When did you last calibrate you pH probe; and 2) what is your alkalinity?

 

[mdb_talon]

Two questions (sorry if you already answered them): 1) When did you last calibrate you pH probe; and 2) what is your alkalinity?

I have two probes and they are calibrated about every 6 months. Over the last several years each has been replaced more than once. Again though this is not an issue for me i resolved this many years ago with an outside air skimmer line. At times i have disconnected the (usually accidently) and the ph starts dropping. In fact when i see low ph the first thing i check is if the airline is still on. The reality is for many people this is a big issue easily fixed with outside air. For many others there is no issue(or there is an issue that outside air wont fix). Just depends on each situation.

I run at a higher than average dkh between 10.5-11.0