Home |
Search |
Today's Posts |
#1
|
|||
|
|||
Does CO2 injection work?
Forgive me for being controversial but I have drawn the following
conclusions on CO2 injection. CO2 injection I can only summise has one achievement, to increase the acidity of an aquarium and thankfully not as effectively as it could. CO2 and H2O form H2CO3 (carbonic acid), the same as in rainfall which naturally is pH 4.5 - 5.5. If I use an air pump and the % make up of atmospheric air is .036% CO2, a 100 litre per hour air pump (very small) is going to deliver .036 of a litre of CO2 into my tank every hour its working. That equates to 1 litre a day or 100000 milligrams of CO2 a day. Now aquatic plants only need about 30 milligrams of CO2 per litre of water so I have delivered 33 times more CO2 (based on a 100 litre tank) than they need. Now here's the kicker. Most of the bubbles go straight to the surface and take the CO2 with them (air pump or CO2 injection) but at the surface create agitation which is very effective in capturing and dissolving air into the water. Without being able to scientifically quantify I would suggest surface agitation in an aquarium is probably responsible for 50-75% of the dissolved gases in an aquarium (in oceans and lakes its near 100%). Although the size of the bubbles will affect the air to water exchange (based on the surface area size a lot of smaller bubbles will release a lot more gas than fewer large ones). So a biowheel is doing much more than CO2 injection ever could. If you want to hypersaturate your aquarium with CO2 a readily available solution would be to pour in a bottle of soda water which is just water hypersaturated with CO2 gas. The only thing is that pH would be extremely low (never measured it but probably less than 4). I haven't done the experiments (but I might) having an interest in creating huge ocean algal blooms in the ocean to suck up some of the excess CO2 we have injected into our environment. I would be interested in wheither anyone has actually measured an increase in dissolved CO2 before and after injection and the corresponding effect on pH. Dean |
#2
|
|||
|
|||
Does CO2 injection work?
"floguru" wrote:
Forgive me for being controversial but I have drawn the following conclusions on CO2 injection. Question - are you basing your conclusions on guesswork, or have you actually used CO2 injection? CO2 injection I can only summise has one achievement, to increase the acidity of an aquarium and thankfully not as effectively as it could. The increasing acidity demonstrates quite clearly that CO2 injection is working, and achieving the result of CO2 gas being dissolved into the water. If I use an air pump and the % make up of atmospheric air is .036% CO2, a 100 litre per hour air pump (very small) is going to deliver .036 of a litre of CO2 into my tank every hour its working. That equates to 1 litre a day or 100000 milligrams of CO2 a day. Now aquatic plants only need about 30 milligrams of CO2 per litre of water so I have delivered 33 times more CO2 (based on a 100 litre tank) than they need. Now here's the kicker. Most of the bubbles go straight to the surface and take the CO2 with them Correct, the bubbles from an air pump leave the tank, and so you're *not* delivering 33 times more CO2 than needed. Everything I've read (apart from sales babble) indicates that bubbles from an air pump have little if any direct effect upon dissolved gasses in the water. In other words, don't consider air pumps at all when you're contemplating CO2 injection, as they're totally unrelated. CO2 injection usually involves a reactor of some sort, be it a simple bell or a powered chamber. I'm using a Hagen diffuser with DIY, generally delivering one bubble per second of CO2 gas into the diffuser. Virtually all of that is dissolved into the water, with only extremely tiny bubbles occasionally leaving the diffuser. So, unlike the air pump case you present, the vast majority of the CO2 in my system is being dissolving into the water, and not directly escaping in the form of bubbles. I would be interested in wheither anyone has actually measured an increase in dissolved CO2 before and after injection and the corresponding effect on pH. Most people doing CO2 injection have, though we work the equation in the other direction. If you know the water hardness and pH, you can calculate the CO2 level. You can find the formula and a handy calculator at Chuck's page: http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm By this formula, my CO2 level without injection was typically about 2.6 ppm. Once I got my CO2 injection working, that level rose to and stays in the mid-teens. With new DIY bottles, CO2 will on occasion rise as high as 30ppm (DIY isn't as stable over time as bottled CO2 injection, unfortunately). So yes, we can and do actually measure an increase in dissolved CO2 when using CO2 injection. -- www.ericschreiber.com |
#3
|
|||
|
|||
Does CO2 injection work?
On Fri, 27 Jun 2003 10:38:52 +1000, "floguru"
wrote: CO2 injection I can only summise has one achievement, to increase the acidity of an aquarium No, most definitely not. CO2 injection raises the concentration of CO2 in the water, greatly increasing plant growth. Plants on land are exposed to 300 to 500 ppm CO2. The water in our aquarium contain around 3ppm without CO2 injection, even with excellent aeration mixing air into the water. Chuck Gadd http://www.csd.net/~cgadd/aqua |
#4
|
|||
|
|||
Does CO2 injection work?
On Thu, 26 Jun 2003 22:31:51 -0500, Eric Schreiber
wrote: So yes, we can and do actually measure an increase in dissolved CO2 when using CO2 injection. Right, and contrary to Dean's incorrect conclusion, the benefit is not simply an acidic pH. If you lower the pH by softening the water and adding peat (tannic acid), you get the low pH, but not the increased CO2 levels, and the plant growth will not improve. In fact, if you have very hard water, you can have a basic pH (over 7.0) with good CO2 injection. If you have very hard water with a KH of 20 degrees KH, and you inject CO2 to raise the level to 15ppm, you will have a pH of 7.6, and you will see the benefit of increased CO2 level in the plant growth, without the acidic pH. Chuck Gadd http://www.csd.net/~cgadd/aqua |
#5
|
|||
|
|||
Does CO2 injection work?
IMHO, the question should be, "Do you want it to work?":
http://mike-edwardes.members.beeb.net/plant/hitech.html Mike. -- Mike Edwardes Tropicals http://mike-edwardes.members.beeb.net |
#6
|
|||
|
|||
Does CO2 injection work?
Using the typical DIY yeast fermentation method of CO2 production, what
level of alcohol diffusion do you get along with the CO2, if any? Seems like that would also be getting into the tank.... "Eric Schreiber" wrote in message ... "floguru" wrote: Forgive me for being controversial but I have drawn the following conclusions on CO2 injection. Question - are you basing your conclusions on guesswork, or have you actually used CO2 injection? CO2 injection I can only summise has one achievement, to increase the acidity of an aquarium and thankfully not as effectively as it could. The increasing acidity demonstrates quite clearly that CO2 injection is working, and achieving the result of CO2 gas being dissolved into the water. If I use an air pump and the % make up of atmospheric air is .036% CO2, a 100 litre per hour air pump (very small) is going to deliver .036 of a litre of CO2 into my tank every hour its working. That equates to 1 litre a day or 100000 milligrams of CO2 a day. Now aquatic plants only need about 30 milligrams of CO2 per litre of water so I have delivered 33 times more CO2 (based on a 100 litre tank) than they need. Now here's the kicker. Most of the bubbles go straight to the surface and take the CO2 with them Correct, the bubbles from an air pump leave the tank, and so you're *not* delivering 33 times more CO2 than needed. Everything I've read (apart from sales babble) indicates that bubbles from an air pump have little if any direct effect upon dissolved gasses in the water. In other words, don't consider air pumps at all when you're contemplating CO2 injection, as they're totally unrelated. CO2 injection usually involves a reactor of some sort, be it a simple bell or a powered chamber. I'm using a Hagen diffuser with DIY, generally delivering one bubble per second of CO2 gas into the diffuser. Virtually all of that is dissolved into the water, with only extremely tiny bubbles occasionally leaving the diffuser. So, unlike the air pump case you present, the vast majority of the CO2 in my system is being dissolving into the water, and not directly escaping in the form of bubbles. I would be interested in wheither anyone has actually measured an increase in dissolved CO2 before and after injection and the corresponding effect on pH. Most people doing CO2 injection have, though we work the equation in the other direction. If you know the water hardness and pH, you can calculate the CO2 level. You can find the formula and a handy calculator at Chuck's page: http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm By this formula, my CO2 level without injection was typically about 2.6 ppm. Once I got my CO2 injection working, that level rose to and stays in the mid-teens. With new DIY bottles, CO2 will on occasion rise as high as 30ppm (DIY isn't as stable over time as bottled CO2 injection, unfortunately). So yes, we can and do actually measure an increase in dissolved CO2 when using CO2 injection. -- www.ericschreiber.com |
#7
|
|||
|
|||
Does CO2 injection work?
On Fri, 27 Jun 2003 01:28:13 -0500, "Stan"
wrote: Using the typical DIY yeast fermentation method of CO2 production, what level of alcohol diffusion do you get along with the CO2, if any? Seems like that would also be getting into the tank.... As long as the yeast/sugar mixture level is lower than the top of the bottle, no alcohol gets into the tank. Chuck Gadd http://www.csd.net/~cgadd/aqua |
#8
|
|||
|
|||
Does CO2 injection work?
I couldn't agree more with Mike! I have two low-tech tanks, a 110 gallon with
about 1 W/gallon of light and a 20-long gallon with about 2 W/gallon. The plants on the big tank grow like weeds, including some species that are supposed to "require" high light. If I had to do more prunning it would not be an enjoyable hobby. The small tank is just getting started, but it's starting to look nice too. -- Victor M. Martinez http://www.che.utexas.edu/~martiv |
#9
|
|||
|
|||
Does CO2 injection work?
On Fri, 27 Jun 2003 00:38:52 UTC, "floguru" wrote:
Forgive me for being controversial but I have drawn the following conclusions on CO2 injection. What's wrong with controversy? There have been a number of replies to this, but I'm going to toss in one more, concentrating on what really happens to CO2 and carbonates in water, which is tricky and misleading unless you look at it right, which no aquarium book I've ever seen tells how to do. I, of course, have it exactly right. Ahem. CO2 injection I can only summise has one achievement, to increase the acidity of an aquarium ... If you want to hypersaturate your aquarium with CO2 a readily available solution would be to pour in a bottle of soda water which is just water hypersaturated with CO2 gas. The only thing is that pH would be extremely low (never measured it but probably less than 4). Yes, around 4. Methyl orange, which switches at 3.7, is used as an indicator when you don't want to see the effects of carbonic acid, but just stronger acids. But "hypersaturate" sounds like a misconception of what's happening when CO2 is injected. See below. I haven't done the experiments (but I might) having an interest in creating huge ocean algal blooms in the ocean to suck up some of the excess CO2 we have injected into our environment. I would be interested in wheither anyone has actually measured an increase in dissolved CO2 before and after injection and the corresponding effect on pH. It's a challenge that probably no one will meet *directly*. I don't even know how you'd go about directly measuring dissolved CO2, though I've done a lot of carbonate measurements, as well as direct measurement of CO2 in air. Fortunately, you can leave the direct measurements to the chemists who create tables of chemical constants, and get the dissolved CO2 level by simple calculations. The research chemists have worked out the relations of all the forms of "total carbonate" listed here. (This may be obvious, but bear with me.) Carbon dioxide, CO2, dissolved in water (what you want, and what our plants want) Carbonic acid, H2CO3, in water Bicarbonate ion, HCO3-, in water Carbonate ion, CO3--, in water. All of these are present if any of them is. The _relative_ amounts depend on the pH in a simple way -- except for the ratio of dissolved CO2 to H2CO3, which is a constant. If you know the pH, then you can calculate the relative amounts of all these forms of carbonate. A simple matter of simultaneous equations. If you know the total amount, then you can figure out how much of each one. If you change the pH by a small amount, they all shift. So this is what we folks with CO2 injection do. Rather, here's what I do with the water that comes out of my tap; others get different water and handle it in different ways. I take tap water with a pH in the high 7's and around 60 parts per million of total carbonate in all forms. I can calculate how much free CO2 there is, with the available tables; 2 parts per million or less, and not enough for good plant growth. I bubble CO2 into it till it's down to pH 7; and I add some kind of carbonate till there are 100 parts per million of total carbonate, and bubble CO2 in to hold it to pH 7. (A couple of teaspoons of baking soda in a 55-gallon tank, as it happens.) I look up the amount of free CO2 in the tables, and wow, I have 14+ ppm of dissolved CO2, which is good for plant growth (Actually, growth is very good even at 4/5 that level.) I could do the whole calculation using the good presentation at http://www.chem.usu.edu/faculty/sbia...ate/Carbonic%2 0Acid.html But it's easier to let others do it, and read the color-coded chart at http://www.sfbaaps.com/reference/table_01.shtml which has total carbonate in units of about 20 ppm, for historical reasons. This should make it fairly clear why you don't need soda water to make the plants grow fast. Very definitely, if you start with very soft water and bubble lots of CO2 into it to get a high level of dissolved CO2, you're going to have acid water and unhappy fish, or dead ones; but carbonates have buffering properties that take care of the problem if you know what to do. Now, about that hypersaturation: Yes, there's too much CO2 in the water this way, far more than will stay there in contact with the air. And you need contact with the air, because the fish need oxygen. So, the CO2 slowly leaks out. Most planted-tank people work hard to keep the air contact down to the minimum needed to keep the fish population happy; and they dribble CO2 into the tank to replace what goes away. (Some CO2, of course, goes away by becoming plant tissue; some by leakage.) I admit that I allow lots of air contact in my system, and I just have to spend more on CO2 to replace what gets away into the air. -- Dan Drake http://www.dandrake.com Outer Planets update: Uranus, Neptune, Pluto, the check in the mail, the weapons of mass destruction. |
#10
|
|||
|
|||
Does CO2 injection work?
Xref: 127.0.0.1 rec.aquaria.freshwater.plants:73372
You make some interesting points. Coincidentally, my tap water is, like yours only 60-70ppm carbonate. In my 100gallon tank, at 2 bubbles per second CO2, I have difficulty in getting the pH below 7.0, which equates to 10-12ppm CO2. To get to the 20ppm CO2 which the gurus recommend, I would need a pH of about 6.75. This would need an awful lot of CO2, and I don't believe my reactor could dissolve at that rate. My question is :- are you saying that adding baking soda will give me "free" CO2? If you could possibly do a little more to convince me, I will certainly give it a try. I think that my CO2 injection rate is so high because I am using the BioLife combined trickle and conventional filters, but can't think of a good way to deactivate the trickle section. Does anyone have any ideas? Paul Davies "Dan Drake" wrote in message news:vhIsdqY67dTD-pn2-RwfEon2rELZt@localhost... On Fri, 27 Jun 2003 00:38:52 UTC, "floguru" wrote: Forgive me for being controversial but I have drawn the following conclusions on CO2 injection. What's wrong with controversy? There have been a number of replies to this, but I'm going to toss in one more, concentrating on what really happens to CO2 and carbonates in water, which is tricky and misleading unless you look at it right, which no aquarium book I've ever seen tells how to do. I, of course, have it exactly right. Ahem. CO2 injection I can only summise has one achievement, to increase the acidity of an aquarium ... If you want to hypersaturate your aquarium with CO2 a readily available solution would be to pour in a bottle of soda water which is just water hypersaturated with CO2 gas. The only thing is that pH would be extremely low (never measured it but probably less than 4). Yes, around 4. Methyl orange, which switches at 3.7, is used as an indicator when you don't want to see the effects of carbonic acid, but just stronger acids. But "hypersaturate" sounds like a misconception of what's happening when CO2 is injected. See below. I haven't done the experiments (but I might) having an interest in creating huge ocean algal blooms in the ocean to suck up some of the excess CO2 we have injected into our environment. I would be interested in wheither anyone has actually measured an increase in dissolved CO2 before and after injection and the corresponding effect on pH. It's a challenge that probably no one will meet *directly*. I don't even know how you'd go about directly measuring dissolved CO2, though I've done a lot of carbonate measurements, as well as direct measurement of CO2 in air. Fortunately, you can leave the direct measurements to the chemists who create tables of chemical constants, and get the dissolved CO2 level by simple calculations. The research chemists have worked out the relations of all the forms of "total carbonate" listed here. (This may be obvious, but bear with me.) Carbon dioxide, CO2, dissolved in water (what you want, and what our plants want) Carbonic acid, H2CO3, in water Bicarbonate ion, HCO3-, in water Carbonate ion, CO3--, in water. All of these are present if any of them is. The _relative_ amounts depend on the pH in a simple way -- except for the ratio of dissolved CO2 to H2CO3, which is a constant. If you know the pH, then you can calculate the relative amounts of all these forms of carbonate. A simple matter of simultaneous equations. If you know the total amount, then you can figure out how much of each one. If you change the pH by a small amount, they all shift. So this is what we folks with CO2 injection do. Rather, here's what I do with the water that comes out of my tap; others get different water and handle it in different ways. I take tap water with a pH in the high 7's and around 60 parts per million of total carbonate in all forms. I can calculate how much free CO2 there is, with the available tables; 2 parts per million or less, and not enough for good plant growth. I bubble CO2 into it till it's down to pH 7; and I add some kind of carbonate till there are 100 parts per million of total carbonate, and bubble CO2 in to hold it to pH 7. (A couple of teaspoons of baking soda in a 55-gallon tank, as it happens.) I look up the amount of free CO2 in the tables, and wow, I have 14+ ppm of dissolved CO2, which is good for plant growth (Actually, growth is very good even at 4/5 that level.) I could do the whole calculation using the good presentation at http://www.chem.usu.edu/faculty/sbia...ate/Carbonic%2 0Acid.html But it's easier to let others do it, and read the color-coded chart at http://www.sfbaaps.com/reference/table_01.shtml which has total carbonate in units of about 20 ppm, for historical reasons. This should make it fairly clear why you don't need soda water to make the plants grow fast. Very definitely, if you start with very soft water and bubble lots of CO2 into it to get a high level of dissolved CO2, you're going to have acid water and unhappy fish, or dead ones; but carbonates have buffering properties that take care of the problem if you know what to do. Now, about that hypersaturation: Yes, there's too much CO2 in the water this way, far more than will stay there in contact with the air. And you need contact with the air, because the fish need oxygen. So, the CO2 slowly leaks out. Most planted-tank people work hard to keep the air contact down to the minimum needed to keep the fish population happy; and they dribble CO2 into the tank to replace what goes away. (Some CO2, of course, goes away by becoming plant tissue; some by leakage.) I admit that I allow lots of air contact in my system, and I just have to spend more on CO2 to replace what gets away into the air. -- Dan Drake http://www.dandrake.com Outer Planets update: Uranus, Neptune, Pluto, the check in the mail, the weapons of mass destruction. |
#11
|
|||
|
|||
Does CO2 injection work?
"Paul Davies" wrote in message ...
You make some interesting points. Coincidentally, my tap water is, like yours only 60-70ppm carbonate. In my 100gallon tank, at 2 bubbles per second My question is :- are you saying that adding baking soda will give me "free" CO2? No, it will only scale up the pH range you need to have a good CO2 level in your tank. A KH of 50ppm(~3 degrees) needs a pH of about 6.5 or so. A KH of 350(~20 degrees) needs a pH of 7.3. Both have the same amount of CO2. One has more Total carbon(CO2 + HCO3) but both have the same amount of CO2. CO2 is what the plant wants. Just figuire out a way to get more into the tank or increase the efficiency of the method which you are dissolving the gas. Regarding trickle filter CO2 losses: it's not the bio tower part, it's the over flow and splashing etc. Sealed trickle sections should not lose any CO2 gases. See George's, Steve's and my comments on the APD regarding this. If you could possibly do a little more to convince me, I will certainly give it a try. I think that my CO2 injection rate is so high because I am using the BioLife combined trickle and conventional filters, but can't think of a good way to deactivate the trickle section. Does anyone have any ideas? Paul Davies Regards, Tom Barr |
#12
|
|||
|
|||
Does CO2 injection work?
Thanks Tom for your comments. I've read the threads, and I'll try to make
some changes to the trickle filter to reduce turbulence. paul davies " wrote in message om... "Paul Davies" wrote in message ... You make some interesting points. Coincidentally, my tap water is, like yours only 60-70ppm carbonate. In my 100gallon tank, at 2 bubbles per second My question is :- are you saying that adding baking soda will give me "free" CO2? No, it will only scale up the pH range you need to have a good CO2 level in your tank. A KH of 50ppm(~3 degrees) needs a pH of about 6.5 or so. A KH of 350(~20 degrees) needs a pH of 7.3. Both have the same amount of CO2. One has more Total carbon(CO2 + HCO3) but both have the same amount of CO2. CO2 is what the plant wants. Just figuire out a way to get more into the tank or increase the efficiency of the method which you are dissolving the gas. Regarding trickle filter CO2 losses: it's not the bio tower part, it's the over flow and splashing etc. Sealed trickle sections should not lose any CO2 gases. See George's, Steve's and my comments on the APD regarding this. If you could possibly do a little more to convince me, I will certainly give it a try. I think that my CO2 injection rate is so high because I am using the BioLife combined trickle and conventional filters, but can't think of a good way to deactivate the trickle section. Does anyone have any ideas? Paul Davies Regards, Tom Barr |
#13
|
|||
|
|||
Does CO2 injection work?
On Wed, 2 Jul 2003 19:47:34 UTC, "Paul Davies"
wrote: You make some interesting points. Coincidentally, my tap water is, like yours only 60-70ppm carbonate. In my 100gallon tank, at 2 bubbles per second CO2, I have difficulty in getting the pH below 7.0, which equates to 10-12ppm CO2. To get to the 20ppm CO2 which the gurus recommend, I would need a pH of about 6.75. This would need an awful lot of CO2, and I don't believe my reactor could dissolve at that rate. My question is :- are you saying that adding baking soda will give me "free" CO2? If you could possibly do a little more to convince me, I will certainly give it a try. Tom Barr has already given a good answer, I see. To change the independent variable from the way he put it: Adding bicarbonate will let you have more dissolved CO2 at your favorite pH level, like 7.0 or whatever, than you would with your plain tap water. It's not free, in that you have to keep pumping CO2 in. First you have to pump extra CO2 to bring the pH back _down_ where you want it after adding the bicarb. Then, because your level of free CO2 is higher than before -- that's what you wanted, after all -- the stuff will escape more rapidly, and you'll have to replace it more rapidly. The too-rapid escape of CO2 because of too much mixing with air would raise the pH if you allowed it to; but in practice that means you'll have to add CO2 a little faster to keep the pH steady. (This is an exercise in saying the same thing several different ways. It's the only way I can grasp problems that have several variables that all affect each other.) -- Dan Drake http://www.dandrake.com Outer Planets update: Uranus, Neptune, Pluto, the check in the mail, the weapons of mass destruction. |
#14
|
|||
|
|||
Does CO2 injection work?
On Wed, 2 Jul 2003 19:47:34 UTC, "Paul Davies"
wrote: You make some interesting points. Coincidentally, my tap water is, like yours only 60-70ppm carbonate. In my 100gallon tank, at 2 bubbles per second CO2, I have difficulty in getting the pH below 7.0, which equates to 10-12ppm CO2. To get to the 20ppm CO2 which the gurus recommend, I would need a pH of about 6.75. This would need an awful lot of CO2, and I don't believe my reactor could dissolve at that rate. My question is :- are you saying that adding baking soda will give me "free" CO2? If you could possibly do a little more to convince me, I will certainly give it a try. Tom Barr has already given a good answer, I see. To change the independent variable from the way he put it: Adding bicarbonate will let you have more dissolved CO2 at your favorite pH level, like 7.0 or whatever, than you would with your plain tap water. It's not free, in that you have to keep pumping CO2 in. First you have to pump extra CO2 to bring the pH back _down_ where you want it after adding the bicarb. Then, because your level of free CO2 is higher than before -- that's what you wanted, after all -- the stuff will escape more rapidly, and you'll have to replace it more rapidly. The too-rapid escape of CO2 because of too much mixing with air would raise the pH if you allowed it to; but in practice that means you'll have to add CO2 a little faster to keep the pH steady. (This is an exercise in saying the same thing several different ways. It's the only way I can grasp problems that have several variables that all affect each other.) -- Dan Drake http://www.dandrake.com Outer Planets update: Uranus, Neptune, Pluto, the check in the mail, the weapons of mass destruction. |
#15
|
|||
|
|||
Does CO2 injection work?
Thanks
Today I tried an experiment. I have 2 Biolife combined trickle/ conventional filters. At 2 bubbles CO2/sec into my 100gall tank, I was getting a pH of 7.05 (10ppm CO2). I switched off one of the filters for a few hours and the pH fell to 6.8 (19ppm CO2) at the same bubble rate, so the point has now been proved. I have now switched the filter back on, but totally submerged, so that the trickle section is ineffective. Paul Davies "Dan Drake" wrote in message news:vhIsdqY67dTD-pn2-B03RboG2v7pW@localhost... On Wed, 2 Jul 2003 19:47:34 UTC, "Paul Davies" wrote: You make some interesting points. Coincidentally, my tap water is, like yours only 60-70ppm carbonate. In my 100gallon tank, at 2 bubbles per second CO2, I have difficulty in getting the pH below 7.0, which equates to 10-12ppm CO2. To get to the 20ppm CO2 which the gurus recommend, I would need a pH of about 6.75. This would need an awful lot of CO2, and I don't believe my reactor could dissolve at that rate. My question is :- are you saying that adding baking soda will give me "free" CO2? If you could possibly do a little more to convince me, I will certainly give it a try. Tom Barr has already given a good answer, I see. To change the independent variable from the way he put it: Adding bicarbonate will let you have more dissolved CO2 at your favorite pH level, like 7.0 or whatever, than you would with your plain tap water. It's not free, in that you have to keep pumping CO2 in. First you have to pump extra CO2 to bring the pH back _down_ where you want it after adding the bicarb. Then, because your level of free CO2 is higher than before -- that's what you wanted, after all -- the stuff will escape more rapidly, and you'll have to replace it more rapidly. The too-rapid escape of CO2 because of too much mixing with air would raise the pH if you allowed it to; but in practice that means you'll have to add CO2 a little faster to keep the pH steady. (This is an exercise in saying the same thing several different ways. It's the only way I can grasp problems that have several variables that all affect each other.) -- Dan Drake http://www.dandrake.com Outer Planets update: Uranus, Neptune, Pluto, the check in the mail, the weapons of mass destruction. |
Reply |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Work, Work, Work | Edible Gardening | |||
FA: DIY CO2 injection system with 5 lb CO2 tank | Freshwater Aquaria Plants | |||
Got CO2 injection system, now where the hell do I get the CO2 tank? | Freshwater Aquaria Plants | |||
Got CO2 injection system, now where the hell do I get the CO2 | Freshwater Aquaria Plants | |||
Help needed w/ CO2 injection | Freshwater Aquaria Plants |