Big Bubbler for pH?

[rygh]

Tidbit: Waterfall style algae scrubbers are also really good for CO2 exchange.
You get a big rapid waterfall.
You get a very rough surface due to algae growth.
And yes, you get algae taking in CO2 and releasing O2.

 

[H2OPlayar]

Tidbit: Waterfall style algae scrubbers are also really good for CO2 exchange.
You get a big rapid waterfall.
You get a very rough surface due to algae growth.
And yes, you get algae taking in CO2 and releasing O2.

So what I am hearing is to clean the algae off the sides of my sump less

 

[BAYMAC]

There was a thread on Reefs.org or Article that calculated the air exchange from air stones vs a weir vs just an agitated open top. A weir was much more effective as you are bringing water to the air vs air to the water and it addresses water surface tension more effectively. Kinda started the Coast to Coast overflow thing. I made one on my 6' tank, was very effective. Maybe see if you can add more weirs in your sump with a fan to make sure you have good air down there. You can also add a weir to some overflow box configurations with some DIY.

I can't find the article as the content from that message board is all gone or difficult to find, but I remember experiments were included in it.

Pretty sure that was in AAOL of which REEFS.COM owns now.

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[Joseph Lee]

There was a thread on Reefs.org or Article that calculated the air exchange from air stones vs a weir vs just an agitated open top. A weir was much more effective as you are bringing water to the air vs air to the water and it addresses water surface tension more effectively. Kinda started the Coast to Coast overflow thing. I made one on my 6' tank, was very effective. Maybe see if you can add more weirs in your sump with a fan to make sure you have good air down there. You can also add a weir to some overflow box configurations with some DIY.

I can't find the article as the content from that message board is all gone or difficult to find, but I remember experiments were included in it.

I guess installing an HOB filter could achieve the similar thing?

 

[rygh]

So I did some quick calculations on the side, perhaps poorly, but hopefully not.

Assuming a large ($50 or so) air pump at 20 LPM.
With a 0.5 mm bubble, you have about the same surface area as a 4'x2' tank.
With a 0.05 mm bubble, you have about 10X the surface area as a 4'x2' tank.

And then there is circulation.

Skimmers are lousy.
Those bubbles generate a froth. That froth does not really move.
So the only real contact that matters is when the bubbles initially mix.

A rising stream of bubbles is probably not so great.
It does create water flow, so there is new water coming in, but not so great, especially
for the bubbles on the inside of the stream.

--- SO --

If you have a weak air pump, larger bubbles, and a simple rising bubble stream, it is probably
pretty close to useless, since it is far less than the surface of your tank.
Same with a crappy skimmer.

But lets say you have a strong air pump, and bubble stream running into a powerhead.
Now you have much smaller chopped bubbles.
Plus you have bubbles rapdily moving throughout the sump.
That could be FAR better than the tank surface.

**BUT**
I have no idea on the exact bubble size!!! Above were simply guesses.
This makes it impossible to make an exact calculation.

 

[JVU]

So I did some quick calculations on the side, perhaps poorly, but hopefully not.

Assuming a large ($50 or so) air pump at 20 LPM.
With a 0.5 mm bubble, you have about the same surface area as a 4'x2' tank.
With a 0.05 mm bubble, you have about 10X the surface area as a 4'x2' tank.

And then there is circulation.

Skimmers are lousy.
Those bubbles generate a froth. That froth does not really move.
So the only real contact that matters is when the bubbles initially mix.

A rising stream of bubbles is probably not so great.
It does create water flow, so there is new water coming in, but not so great, especially
for the bubbles on the inside of the stream.

--- SO --

If you have a weak air pump, larger bubbles, and a simple rising bubble stream, it is probably
pretty close to useless, since it is far less than the surface of your tank.
Same with a crappy skimmer.

But lets say you have a strong air pump, and bubble stream running into a powerhead.
Now you have much smaller chopped bubbles.
Plus you have bubbles rapdily moving throughout the sump.
That could be FAR better than the tank surface.

**BUT**
I have no idea on the exact bubble size!!! Above were simply guesses.
This makes it impossible to make an exact calculation.

An air stone that makes tiny bubbles with a strong air pump in a chamber that has high counter-direction flow and high turnover (like my overflow chamber) and a long height/dwell time (the entire height of the tank) seems like it is optimal by your calculations. With the bonus of not having micro bubbles popping and spraying everywhere in the sump.

 

[Qwiv]

So I did some quick calculations on the side, perhaps poorly, but hopefully not.

Assuming a large ($50 or so) air pump at 20 LPM.
With a 0.5 mm bubble, you have about the same surface area as a 4'x2' tank.
With a 0.05 mm bubble, you have about 10X the surface area as a 4'x2' tank.

And then there is circulation.

Skimmers are lousy.
Those bubbles generate a froth. That froth does not really move.
So the only real contact that matters is when the bubbles initially mix.

A rising stream of bubbles is probably not so great.
It does create water flow, so there is new water coming in, but not so great, especially
for the bubbles on the inside of the stream.

--- SO --

If you have a weak air pump, larger bubbles, and a simple rising bubble stream, it is probably
pretty close to useless, since it is far less than the surface of your tank.
Same with a crappy skimmer.

But lets say you have a strong air pump, and bubble stream running into a powerhead.
Now you have much smaller chopped bubbles.
Plus you have bubbles rapdily moving throughout the sump.
That could be FAR better than the tank surface.

**BUT**
I have no idea on the exact bubble size!!! Above were simply guesses.
This makes it impossible to make an exact calculation.

I'll try to explain/remember the air pumped in vs air brought to water surface as is has to do with the volume/concentration of air. Ignore all the incorrect terms as I'm not a chemist.

While chopping the air bubbles into smaller bubbles created more surface area, it does not address the differential concentrations in air exchange. Imagine pumping in x liters of air to mix with the water with the simple assumption is CO2 out, O2 in. The air in the bubble will exchange O2 with the water giving CO2 into that bubble until the concentration of CO2 in the bubble raises. As you add CO2 to the bubble, gas exchange slows, hindering gas exchange. The CO2 in the bubble is trapped until it pops and the higher the CO2 in the bubble, the less effective gas exchange is. Chopping the bubble up just makes this process happen faster, but the limit of say clean air is the air pumped in by the pump, which you can never exceed.

Take that same surface area of water and expose it to your room where the volume of air is so large, the CO2 off gassed by the water will not depreciably effect the O2 in the room without killing you. The theoretical ceiling to gas exchange is much higher due to the volume of air.

This ignores a lot of interactions for simplicity but was the point as I remembered it. Surface Tension in a bubble also had an impact as well with the benefits to a weir vs bubble.

 

[Qwiv]

I guess installing an HOB filter could achieve the similar thing?

Everything you do to increase water to air interactions is a benefit. Its all about the best bang for the buck and what you can realistically achieve. Your tank will inevitably have design limitations and every piece of equipment you add has an energy and maintenance cost. Everyone needs to look at that themselves. I liked the Weir as it has basically no energy costs and little maintenance costs, so the cost/benefit is extremely high.

"Pretty sure that was in AAOL of which REEFS.COM owns now."
Yah, probably. I just could not locate it with a quick search. I am sure it is out there. Glad someone maybe remembers it as I could just be crazy.

 

[rygh]

I'll try to explain/remember the air pumped in vs air brought to water surface as is has to do with the volume/concentration of air. Ignore all the incorrect terms as I'm not a chemist.

While chopping the air bubbles into smaller bubbles created more surface area, it does not address the differential concentrations in air exchange. Imagine pumping in x liters of air to mix with the water with the simple assumption is CO2 out, O2 in. The air in the bubble will exchange O2 with the water giving CO2 into that bubble until the concentration of CO2 in the bubble raises. As you add CO2 to the bubble, gas exchange slows, hindering gas exchange. The CO2 in the bubble is trapped until it pops and the higher the CO2 in the bubble, the less effective gas exchange is. Chopping the bubble up just makes this process happen faster, but the limit of say clean air is the air pumped in by the pump, which you can never exceed.

Take that same surface area of water and expose it to your room where the volume of air is so large, the CO2 off gassed by the water will not depreciably effect the O2 in the room without killing you. The theoretical ceiling to gas exchange is much higher due to the volume of air.

This ignores a lot of interactions for simplicity but was the point as I remembered it. Surface Tension in a bubble also had an impact as well with the benefits to a weir vs bubble.

Not saying you are wrong, but I can see two issues with the saturation problem:

1) A bubble is only around for a few seconds normally. (Other than a skimmer or some micro-bubbles)
It would really surprise me if it reached saturation level in that short of a time.

2) Tiny amount of CO2 exchange.
A liter of water has about 1 gram of CO2 in it. We might be hoping to get rid of maybe 0.1 grams over the period of a day.
A liter of air is about 1.3 grams, and we are pushing through 28,800 liters per day through the air pump.
So the amount diffused seems negligible compare to the amount going through.

 

[rygh]

An air stone that makes tiny bubbles with a strong air pump in a chamber that has high counter-direction flow and high turnover (like my overflow chamber) and a long height/dwell time (the entire height of the tank) seems like it is optimal by your calculations. With the bonus of not having micro bubbles popping and spraying everywhere in the sump.

Definitely seems pretty good.
You rely on your return pump though, not a powehead, which is substantially less flow.
Plus, generating tiny bubbles may be an issue. You can chop them, or you can use higher pressure through a smaller pore. The latter reduces air flow.

 

[rygh]

Everything you do to increase water to air interactions is a benefit. Its all about the best bang for the buck and what you can realistically achieve. Your tank will inevitably have design limitations and every piece of equipment you add has an energy and maintenance cost. Everyone needs to look at that themselves. I liked the Weir as it has basically no energy costs and little maintenance costs, so the cost/benefit is extremely high.

"Pretty sure that was in AAOL of which REEFS.COM owns now."
Yah, probably. I just could not locate it with a quick search. I am sure it is out there. Glad someone maybe remembers it as I could just be crazy.

For a weir, surface area is width of sump * height of drop. Likely around 24" x 4".
That is pretty small compared to the surface are of your tank, so I am a bit skeptical on getting great results overall.
But I agree that flow and surface agitation / boundary would be GREAT. And it is basically free.

 

[Blaise006]

I think PH is so much more important than most give it credit for. Since I moved from 8.1-8.3 to 8.5-8.7 I have seen healthier tissue, greater polyp extension, and denser skeletons in the last few months. I’m just one example but I will never run a tank lower ever again or until my tank tells me otherwise.

I recommend kalk over CO2 scrubber, but I use both.

 

[Qwiv]

Definitely seems pretty good.
You rely on your return pump though, not a powehead, which is substantially less flow.
Plus, generating tiny bubbles may be an issue. You can chop them, or you can use higher pressure through a smaller pore. The latter reduces air flow.

For a weir, surface area is width of sump * height of drop. Likely around 24" x 4".
That is pretty small compared to the surface are of your tank, so I am a bit skeptical on getting great results overall.
But I agree that flow and surface agitation / boundary would be GREAT. And it is basically free.

They addressed the top of the tank too. Wish I could find the article. The water at the top of your tank is less than perfect as it is not as mixed as we think assuming avg. tanks. We can see it moving, but is it circulating? I have good areas of my tank right now that has floaters on it that take a while to get to the overflow and flakes don't instantly disappear. So that water/air boundary is not perfect. Now water flowing over a weir is as close to perfect as you are going to get with the wider the weir, the better. You can calculate the amount of new water crossing over that weir into liters per hour, but the top of the tank, you would need to know how often the water at the surface is really circulated to calculate liters per hour. I know 100% of my return pump goes over the overflow, but less then that spreads across the surface of the water.

 

[Qwiv]

I think PH is so much more important than most give it credit for. Since I moved from 8.1-8.3 to 8.5-8.7 I have seen healthier tissue, greater polyp extension, and denser skeletons in the last few months. I’m just one example but I will never run a tank lower ever again or until my tank tells me otherwise.

I recommend kalk over CO2 scrubber, but I use both.

How on earth did you get that high? That is the highest I have heard someone go for and never read anything on levels that high. Assuming you triple checked that PH probe. I have every alarm to stop anything that raises PH at 8.3. Can you keep 8.8-.7 stable? You would need a lot of uptake CA/Alk for Kalk to not precipitate out.

 

[Qwiv]

Not saying you are wrong, but I can see two issues with the saturation problem:

1) A bubble is only around for a few seconds normally. (Other than a skimmer or some micro-bubbles)
It would really surprise me if it reached saturation level in that short of a time.

2) Tiny amount of CO2 exchange.
A liter of water has about 1 gram of CO2 in it. We might be hoping to get rid of maybe 0.1 grams over the period of a day.
A liter of air is about 1.3 grams, and we are pushing through 28,800 liters per day through the air pump.
So the amount diffused seems negligible compare to the amount going through.

With a big enough air pump you can change the world. Why I said the volume of air in the pump would be your limit. At some point you will just run into salt creep and bubbles in the display too. I can't find the article to see if they had shitty air pumps, so I can only go off what remained in my head. The details of the comparisons are long gone.

I don't think reaching saturation was the point, maintaining the greatest differential is. Like bubbling pure O2 vs just Air.

 

[rygh]

They addressed the top of the tank too. Wish I could find the article. The water at the top of your tank is less than perfect as it is not as mixed as we think assuming avg. tanks. We can see it moving, but is it circulating? I have good areas of my tank right now that has floaters on it that take a while to get to the overflow and flakes don't instantly disappear. So that water/air boundary is not perfect. Now water flowing over a weir is as close to perfect as you are going to get with the wider the weir, the better. You can calculate the amount of new water crossing over that weir into liters per hour, but the top of the tank, you would need to know how often the water at the surface is really circulated to calculate liters per hour. I know 100% of my return pump goes over the overflow, but less then that spreads across the surface of the water.

Very true that tank surface can be a problem.
But if so, why not fix that first?
Just point a powerhead up a bit. Massive boundary layer flow and surface agitation. Better shimmer also.

Maybe I am misunderstanding.
Is the weir suggestion building some tower with overflowing water?
That might be a big help, since it could be a large surface.
I was really thinking the little weir in the sump to keep skimmer water level stable.

 

[Qwiv]

Very true that tank surface can be a problem.
But if so, why not fix that first?
Just point a powerhead up a bit. Massive boundary layer flow and surface agitation. Better shimmer also.

Maybe I am misunderstanding.
Is the weir suggestion building some tower with overflowing water?
That might be a big help, since it could be a large surface.
I was really thinking the little weir in the sump to keep skimmer water level stable.

Anything that flows water over a level edge so a baffle in the sump make one assuming you can manage the water level differences. Want it wide as possible and level. The bigger the drop the better assuming it isn't causing turbulence creating other issues. Look up coast to coast overflows. Anthony Calfo made them popular.

Lots of ways to make the surface better. I have MP10s so I am limited to what I can personally do for the surface. I am assuming @JVU has already hit on the easy stuff with power heads looking for the next improvement. Widening the overflow across the top of your tank can be an easy DIY on some tanks.

 

[JVU]

I think PH is so much more important than most give it credit for. Since I moved from 8.1-8.3 to 8.5-8.7 I have seen healthier tissue, greater polyp extension, and denser skeletons in the last few months. I’m just one example but I will never run a tank lower ever again or until my tank tells me otherwise.

I recommend kalk over CO2 scrubber, but I use both.

It’s pretty difficult to keep pH at 8.5-8.7 in a reef tank. Your calcium and alk would be expected to have a lot of abiotic precipitation at that pH and you would just be fighting that constantly. Also every non-algae organism respirating in your tank plus any gas exchange with room air would constantly be pulling it downward. I’m assuming you have calibrated your pH probes? My first guess would be that they have drifted and your pH isn’t really that high. But certainly could be.

 

[Blaise006]

It’s pretty difficult to keep pH at 8.5-8.7 in a reef tank. Your calcium and alk would be expected to have a lot of abiotic precipitation at that pH and you would just be fighting that constantly. Also every non-algae organism respirating in your tank plus any gas exchange with room air would constantly be pulling it downward. I’m assuming you have calibrated your pH probes? My first guess would be that they have drifted and your pH isn’t really that high. But certainly could be.

I calibrate quarterly and have multiple probes. I’m confident where is has run for the last few months.

Edit: I would never run that high using 2-part and I’m not even sure it would be possible. Regardless I am not alone in this approach. I recommend checking out chunningham reefs where I implemented this approach from.

 

[JVU]

I calibrate quarterly and have multiple probes. I’m confident where is has run for the last few months.

Edit: I would never run that high using 2-part and I’m not even sure it would be possible. Regardless I am not alone in this approach. I recommend checking out chunningham reefs where I implemented this approach from.

Sounds like you are taking this approach after doing your homework and have good results, so that’s great. I personally wouldn’t recommend people to aim that high if the goal is just a healthy reef environment with some margin for error as things come up. In my opinion 8.2-8.3 is optimal and going too high or too low are both risky and to be avoided.

But it sounds like your goal is to supercharge stony coral growth, so in that regard and in a very tightly controlled system it may well be better.