# How many bubbles?



## LilLou (Apr 23, 2006)

Just got the CO2 tank, regulator, and sensor now does anyone have an idea of how many bubbles/sec or bubbles per minute to set this thing at?
:help:
Just asking for a guesstimate. 

Tank 75 Gal

Thanks Lou


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## Bert H (Mar 2, 2004)

Start at a slow rate and keep track of your pH changes. I would say around one bubble every couple of seconds for a tank that size. My guess is you will need a higher flow rate, but a lot depends on the efficiency of your reactor, your filtration system and to some degree your water make up. Gradually adjust it as needed.

Two things to check for. One is your fish, make sure they're not gasping for air at the surface. The second one is to take a sample of your tank water and let it sit out 24hours to degas on your countertop. Measure its pH. The pH you want to aim for in your tank will be 1.0 unit below the measured degas pH. That will yield approx 30ppm CO2.


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## LilLou (Apr 23, 2006)

Bert

PH has been a constant 7.2 since before the end of cycle.

PH monitor should control ph drop, it has a spot to plug in the manifold solenoid.

I was looking for a ph drop of about .6 for a co2 of approx 20ppm

according to charts at 4kh and a ph of 6.6 = 20ppm


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## Bert H (Mar 2, 2004)

A kh of 4 is pretty much ideal for a tank, you're lucky! If 20 is what you want, go for it. You have some room to increase it if you find you need to later on. Make sure your probe is kept properly calibrated.


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## LilLou (Apr 23, 2006)

I live in SI, NY and yes I am pretty lucky. My soap lathers when I use it.
When I go away to someplace and they have hard water in that area I go beserk when I use soap because there are no suds like i'm used to.


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## hoppycalif (Apr 7, 2005)

LilLou said:


> Bert
> 
> PH has been a constant 7.2 since before the end of cycle.
> 
> ...


0.6 drop in PH would give you 12-16 ppm CO2, not 20, and that isn't enough. Shoot for at least 0.8 drop, and preferably 1.0. This shouldn't harm the fish, and will help a lot in preventing BBA.


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## magicmagni (Aug 19, 2004)

Actually the CO2 demand really depends on the amount of light. Anything around 2 WPG it probably doesn't matter. Getting around or over 3wpg you will be limiting plant growth and gambling with having an BBA outbreak. Adding more than needed won't harm anything though. CO2 is cheap and it's proven that 30ppm of Co2 will not harm any fish so my recommendation would be to just set it around that point. The recommendation of 1unit PH drop is a good one. You can also look at a Co2 chart and measure your KH and PH to find out the ppm of Co2 dissolved in your water. If for some reason you don't want a low ph then you can add baking soda to your water to raise the KH and shift the PH up a little; however I see no reason to do this.

Note on PH controllers: You are relying solely on the electronics to control your Co2 delivery. Stray voltages from lights, debris on probe and changes in parameters that it cannot measure will throw off accurate administration of Co2 so be very diligent about calibrating and cleaning the probe bi-weekly. Also keep a keen eye on any changing in KH. This is one parameter that your controller has no idea about and this is a critical piece of the equation in the PH/KH/ CO2 relationship. Just one degree of change in the hardness can Knock off the amount of Co2 that gets injected and stress the fish (if too high*) and cause a limit in plant growth if too low.


Good luck!


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## LilLou (Apr 23, 2006)

have the test tube out overnight to do a de gassed ph test will report that tommorrow.

Probe manufacturer said to calibrate the probe every month, although every other week wouldn't be too much of a stretch.

Didn't think about the kH test will do that tonight also just to make sure there were no drops or raises.

I had a carbo plus before this and it didn't do the job but the kH never dropped with that. 

Funny thing though pH monitor shows a pH about .2 degrees higher than test kit.

Maybe test kit need to be replaced. READ OLD. This was after I recalibrated the monitor for the second time.

Set the monitor at 7.0 (higher than I would have liked) just in case because I didn't have time to check everthing properly. When I got home last night Ph monitor showed pH at 8.0 checked this morning and it had dropped to 7.0 and solenoid was off.

Made the reactor yesterday, it seems to be woking well. Also made a spraybar that I forgot to get a hose barb adapter for. One more trip to the Depot. Oh well I need to get 4' fluorescents anyway for the basement.

Thanks for the replies.

Lou


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## neil1973 (Feb 23, 2006)

You should definitly be ok with a ph drop of 1.0. My tank has a Kh of 4, ph of 6.2 and a drop of about 1.5.

But take it slowly and watch your fish especially at night if you are using a ph controller constantly 24hours a day.


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## LilLou (Apr 23, 2006)

The Marineland Emperor 400 stirs the surface of the water up pretty good so I think I am okay on the whole o2/co2 thing but I will check them to see if there are any signs of poisoning. Everyone looked okay last night.

It is possible to have a high O2 concentration as well as a decent co2 concentration. I do believe I read that somewhere.

Lou


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## John N. (Dec 11, 2005)

LilLou said:


> It is possible to have a high O2 concentration as well as a decent co2 concentration. I do believe I read that somewhere.
> 
> Lou


Yes, I believe CO2 and O2 are independent of each other. So you can accomplish both. Most likely your fish will be okay when injecting your CO2 as above.

-John N.


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## hoppycalif (Apr 7, 2005)

We prove that you can have both gases dissolved in very high ppm everytime we get pearling. That means the water is O2 saturated, and we generally got there by having 30+ ppm CO2 in the water.


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## LilLou (Apr 23, 2006)

de gassed pH according to test kit is 7.0
Now I am showing a difference of .2 between pH meter and test kit according to 
tests straight out of the tank.

Had some pearling when I got home last night so things must be heading in the right direction.

Green algae has set in now in place of the brown.

Hopefully the increased CO2 will help with this.

I now have the PH monitor set to 6.8 with no obvious signs of distress to the fish.

Also the KH has risen to 5

So according to the chart I should have a co2 concentration of about 23.8

Let me know if any of this makes sense to someone with a little more experience than myself.

Thanks for all the help 
Lou


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## Bert H (Mar 2, 2004)

Assuming you have calibrated your pH monitor correctly with the standard solutions of pH7 and pH4 (and pH 10 if present), I would trust your monitor more than your kit. The kit requires an interpretation of color compared to a chart. Of course, you can also calibrate your kit by using pH7 buffer and seeing the color it gives you in comparison. Keep in mind that pH monitors can be affected by the electronic ballasts of our lights.



> de gassed pH according to test kit is 7.0
> Now I am showing a difference of .2 between pH meter and test kit according to
> tests straight out of the tank.


So you have taken a sample of your tank water, let it sit out for 24 hours on your countertop and measured its pH and the results are either 7.0 or 7.2, depending on whether it's the kit or the probe. Is that correct? So the target pH you're aiming for then would be 6.0 or 6.2 depending on which of the original readings are accurate. That will yield approx 30ppm of CO2.


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## CherylR (Aug 12, 2004)

Start the flow slowly, first thing in the morning when you can be around most of the day. Check often and look carefully at the fish. The *next* morning, check the fish first thing and aerate if the fish are gasping at all. I find that it takes a few days for the plants to produce enough oxygen to last the fish overnight.

Cheryl


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## LilLou (Apr 23, 2006)

So I don't go by the chart using a KH of 5 and a pH of 6.8?

The oxygen I am not too worried about because the filter stirs the surface of the water up pretty good.

A PH of 6.0 is very low is it not?

I had pearling yesterday afternoon when I got home from work.


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## hoppycalif (Apr 7, 2005)

Most people seem now to understand that PH is not as important to fish as was once thought. Rainwater is acidic in PH, so if fish were really sensitive to PH they would tend to die off after every big rainfall. GH and KH are probably more important to the fish than PH. (Of course a really low PH, like 4.0, is obviously going to be harmful.) If you follow what Bert recommended you are likely to be right where you want to be.

Your statement about the filter stirring up the water does concern me though. What kind of filter are you using? It is good to have surface movement, so that any duckweed, for example, circulates around instead of being still in the water. But, heavy water movement will dissipate CO2 and make it hard to reach the concentration you need.


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## LilLou (Apr 23, 2006)

hoppycalif said:


> Your statement about the filter stirring up the water does concern me though. What kind of filter are you using? It is good to have surface movement, so that any duckweed, for example, circulates around instead of being still in the water. But, heavy water movement will dissipate CO2 and make it hard to reach the concentration you need.


Hoppy,

I currently have an emperor 400 HOB. The surface of the water isn't like the rapids, but it does move/agitate the surface of the water. As far as the CO2 dissapating, I turned the CO2 monitor down to 6.5 last night with the lights still on and it continued to drop. So I think I am okay there. Using an inline DIY reactor. Dimensions 2" diameter 12" long, 1/2" inlet and outlet, 14-- 1/2" Bio pin balls in there.

Last question, The chart everyone refers to shows the maximum amount of CO2 you could get into the water? EX my PH is 6.5 and KH is 5 according to chart the most CO2 I could have in the water would be 47.4??

Thanks for all the help
Lou


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## Bert H (Mar 2, 2004)

> Last question, The chart everyone refers to shows the maximum amount of CO2 you could get into the water? EX my PH is 6.5 and KH is 5 according to chart the most CO2 I could have in the water would be 47.4??


No. The solubility of CO2 in water is very high and you can easily get ppm's in the hundreds if you add sufficient CO2. The chart just happens to cut off there.


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## hoppycalif (Apr 7, 2005)

That KH/PH chart for determining ppm of CO2 can really mislead you. If you have some driftwood in the tank, it can release tannins, which lower the PH a bit. If your KH (alkalinity) is made up of more than carbonates or bicarbonates your real KH, as far as determining CO2 is concerned is not what he test says. So, many of us have used that chart and found that, according to it, we have 100 ppm of CO2 in the water, which should kill all of the fish, but we really have far less.

Another problem in measuring CO2 is that the test kits require you to decide which color on a piece of paper or plastic most closely matches that of a transparent sample in a cylindrical test tube, and that can be very difficult to do. KH tests seem to be easier to interpret, but the margin of error on them plus the margin of error on PH can make the CO2 test be very inaccurate. I think the most accurate way to do this is to use the difference in PH of a degassed sample of your tank water and the water in the tank. At least then you are only assuming that both samples have the same KH, which they should, and you are assuming that the degassed sample has 3-4 ppm of CO2, which is probably pretty close to reality. To make this test most accurate a calibrated PH meter, with an accuracy better than +/- 0.1 is the best thing to use.


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## LilLou (Apr 23, 2006)

Thanks hoppy

So the chart doesn't really affect the CO2 level because of variables beyond our control.

In a perfect test solution where we knew the kH was only composed of carbonate and bi carbonates, and there was also nothing present in the water to alter pH then the chart would be accurate but since we can't guarantee these above conditions the chart should be used with a grain of salt as it were?

I think the light bulb just went on. I understood the degassed ph reading and deop by 1 on the ph scale but got confused when referring to the chart and seeing that I would be in the 100's with CO2,

Thanks 
Lou


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## hoppycalif (Apr 7, 2005)

You seem to understand it pretty well. The chart is based on the equation that relates PH, KH and ppm CO2, where the water gets its alkalinity only from carbonates and bicarbonates, and its acidity only from carbonic acid from CO2. It is a theoretical equation that works very well when the asumptions are all met. But, many of us have found that our water doesn't meet those asumptions, so the chart, for some reason, always gives a too high number for CO2 ppm. By contrast, measuring only PH for two conditions, with the same KH for each, and knowing reasonably well what the ppm CO2 is for one case, gives a more accurate measure of ppm CO2 for the other case. The case where we know the ppm of CO2 reasonably well (I think) is a sample of tank water allowed to sit in the open air for several hours - leaving it with 3 to 4 ppm CO2.

As soon as I find the time and get my PH meter working right and consistently, I plan to do some more experimenting to try to verify both the number of hours we need to wait for the sample to degas, and what the final ppm of CO2 in it is. (I will do that by using distilled water, with only bicarbonate of soda in it for alkalinity, where the KH/PH/CO2 chart should be very accurate. Plus, plotting the PH vs. time for a tank sample for a couple of days. I wish many others would try this too!)


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