# How Many?



## Sunny (Aug 26, 2009)

So I have my co2 all hooked up and ready to go, full tank co2, regulator, bubble counter, co2 reactor, PH controller, and a drop checker. This is an established 90 gallon tank with fish and plants in it already. My question is where do I start? One bubble per second? 2 bubbles per second? 5 bubbles per second? What determines the rate of flow BPS? Is it how fast I want to get there? Am I missing something?

Thanks for your input


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## gucci17 (Oct 11, 2007)

Start with one bps just to be safe and go up from there. Just gage it by your drop checker and the reaction from you fish. With a 90gal tank, you've got quite a bit of room for margin of error.


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## Calmer (Mar 9, 2008)

For my 90 gal. I have mine set for about 2 bps and my ph is around 6.6-6.8. I don't use a ph controller with my setup. Instead I use a timer to shut the co2 off when the aquarium lights go off.

This website will probably help explain a lot:
http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm


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## Sunny (Aug 26, 2009)

Thanks I have that link saved to my favourites. My KH is pretty high at 13 so I wondered if that would have any effect on the drop checker, I don't think it will as I filled the drop checker with the aquarium water that was KH 13. If I go by the calculator on Chuck's page, a PH of 7.0 with a KH of 13 should give me CO2 of 39 ppm which is fine, but at what ppm will the drop checker turn green?


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## Mr Fishies (Sep 21, 2007)

Well, if you fill the drop checker with a 4 dkH solution it will turn green ~30 ppm. I don't currently use a drop checker, so this is just my calculations made using this page which is an online calculator to make a solution of X dKH that will turn green at a given ppm.

I think at 83ppm, your checker will turn green...

A few other links for your collection:

DB's post on Drop checkers and 4 dkH solutions

Drop Checkers/CO2 Indicators-Why and How


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## Sunny (Aug 26, 2009)

Thanks Ian, how did you arrive at 83 ppm?


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## Mr Fishies (Sep 21, 2007)

Sunny said:


> Thanks Ian, how did you arrive at 83 ppm?


Using the calculator in the link, which is intended to provide a drop checker solution that will turn green at a given ppm of your choosing, I bumped the desired PPM up until 83 ppm where the solution dKH was 11.014.

So, unless I'm out in left, that means your drop checker, filled with 11dkH water from your tank won't be green until 83ppm.

Hence my inclusion of the link on how to make a 4dKH solution that would turn green at 30 ppm.

Why, did I miss something obvious?


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## Sunny (Aug 26, 2009)

No I think I did duh!  

The 83 ppm is based on a PH of 6.6 though right?

I'm going to make some KH4 solution up tomorrow and try it out. I also ordered a "Greenleaf" drop checker online tonight.


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## Darkblade48 (Jan 28, 2008)

Sunny said:


> My KH is pretty high at 13 so I wondered if that would have any effect on the drop checker, I don't think it will as I filled the drop checker with the aquarium water that was KH 13.


Your kH should not affect your drop checker readings in anyway. You should not be using tank water inside your drop checker anyway. You should be using a 4 dkH reference solution at all times.



Sunny said:


> If I go by the calculator on Chuck's page, a PH of 7.0 with a KH of 13 should give me CO2 of 39 ppm which is fine, but at what ppm will the drop checker turn green?


The pH of your tank (7.0) and your tank kH (13 dkH) is not a good indicator of the amount of CO2 in your tank. This is because the pH/kH/CO2 relationship can only be used when carbonate is the only ionic species contributing to carbonate hardness. In the aquarium, this is not the case, as there are other buffers that may act upon the kH. As a result, you cannot use the pH/kH/CO2 relationship in a tank.

When you use a drop checker, you should be using a 4 dkH reference solution. As the CO2 dissolves into the reference solution, the pH will drop. With the bromothymol blue indicator, as the pH drops, the pH indicator will change to a green colour around a pH of 6.6, which is equivalent to 30 ppm of CO2.



Mr Fishies said:


> I don't currently use a drop checker, so this is just my calculations made using this page which is an online calculator to make a solution of X dKH that will turn green at a given ppm.
> 
> I think at 83ppm, your checker will turn green...





Sunny said:


> Thanks Ian, how did you arrive at 83 ppm?


You are using the calculator incorrectly. Instead of thinking "at what level of CO2 will the drop checker change colour", you should think of it conversely, i.e. "when the drop checker changes colour, at what level is my CO2?"

Because of some misinterpretation, you arrived at a strange number (83 ppm, 11 dkH). The calculator, however, is not wrong. It indicates that when you are using an 11 dkH reference solution inside the drop checker, that the reagent will turn green (i.e. reach a pH of 6.6) when the CO2 levels are 83 ppm.



Mr Fishies said:


> So, unless I'm out in left, that means your drop checker, filled with 11dkH water from your tank won't be green until 83ppm.
> 
> Hence my inclusion of the link on how to make a 4dKH solution that would turn green at 30 ppm.
> 
> Why, did I miss something obvious?


And here, it seems to be clarified.



Sunny said:


> The 83 ppm is based on a PH of 6.6 though right?


Yes, it is.



Sunny said:


> I'm going to make some KH4 solution up tomorrow and try it out. I also ordered a "Greenleaf" drop checker online tonight.


4 dkH reference solution is quite easy to make, especially if you reduce error by making large batches (i.e. instead of trying to weigh out (say) 0.002 grams, you are weighing out 2 grams instead, etc). However, if you have access to more accurate equipment (i.e. analytical scales, volumetric flasks), then by all means, go ahead and use them. That is what I do


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## Sunny (Aug 26, 2009)

You should not be using tank water inside your drop checker anyway. You should be using a 4 dkH reference solution at all times. 


Yes but the people at Red Sea don't tell you that, they actually tell you to use the aquarium water. Someone should enlighten them, as they are leading people down the wrong path.

Thanks again Anthony for your help.


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## Mr Fishies (Sep 21, 2007)

Darkblade48 said:


> You are using the calculator incorrectly. Instead of thinking "at what level of CO2 will the drop checker change colour", you should think of it conversely, i.e. "when the drop checker changes colour, at what level is my CO2?"


I know that's not how the calculator was intended to be used, I was trying to answer his question about when his drop checker would turn green...since he was starting with 11dKH in his checker I had to use the calculator "backwards"...sort of...bah, forget it...I've been told since grade school that I have a knack for doing things unconventionally (wrong?) but getting the right answer.


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