Disposable fluval CO2.. nervous.. what else do I need? - Page 3 - The Planted Tank Forum
Old 05-14-2019, 04:21 PM
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Quote:
Originally Posted by cl3537 View Post
I think you fundamentally don't understand that chart, I was in your shoes 3 months ago so I'll try one more time to explain it. In my opinion(and many others) more people have been misled by that chart than it helped.

First as an approximation the chart assumes your starting pH degassed of your tank water has 3ppm CO2 in it and nothing else. Your water must nothing in it Carbonates for hardness which is difficult to know unless you use RODI. (This is the approximation that fails and makes the chart unuseable for most)

To give you some typical theoretical values for what your degassed pH (from your tap/tank before CO2 injection) should be in order for the chart to be accurate here are some:

kh=1 ph=7
kh=5 ph=7.7
kh=10 ph=8

Now lets look on that chart at each kH value for what your final pH(after CO2 injection) should be for exactly 30ppm of CO2.

kh=1 ph=6
kh=5 ph=6.7
kh=10 ph=7

Exactly a one point drop gives you 30ppm at all Kh values in the chart(which isn't accurate at low Kh but I won't get into that now).

The chart is calculated using the following formula 3*kh*10^(7-ph)=[Co2]ppm

I will reiterate again that the chart does not take into consideration your starting pH it assumes it based on 3ppm CO2 dissolved in water and no other hardness but Carbonates.

Now I will ask you a question based on the chart:

1) If you have kh=5 water and your pH is 7.2(not 7.7) and your pH drop is to 6.7 how much CO2 can you estimate you injected using the chart? (Do you think it is the same as a tank with starting ph of 7.7?).

2) How about my tank which has a degassed pH of 8.0 and a kh=5 and my pH drop is to 6.5 how much CO2 should I assume I injected into my tank from the chart?

If you can answer those two questions you have gone far beyond the simple calculations used to construct that chart.

You don't have to take my word for it perhaps @plantbrain (Tom Barr here) might explain or you can go on barrreport.com and he might reply.

I think that this warrants more discussion, but I don't want to hijack LBL's thread more with this. If you don't mind, I will post another thread on the topic when I have a little more time to get into it. I haven't derived this one myself in awhile (since I was teaching this 15 years ago), so I probably should to compare to this chart and give it the proper rigor.

“Science, my lad, is made up of mistakes, but they are mistakes which it is useful to make, because they lead little by little to the truth.” -Jules Verne
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Old 05-14-2019, 04:22 PM
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Quote:
Originally Posted by livebearerlove View Post

QUESTION: so do I leave it on 24/7?
Beautiful tank, it is inspiring to see what you can grow even without CO2.
I ran CO2 24/7 (w/inline diffusor) in a 17gallon with a 1.45(day minimmum) - 1.6(night maximum) ph drop for over a year, and will continue to run it that way in my new scape.

In small tanks its practical to run CO2 24/7, why bother buying an expensive regulator or a cheap solenoid that could malfunction. Your kit has a hard to adjust valve but that is perfectly fine if you set it and forget it at such low CO2 tank pressures.

Watch your fish and pH the first night or two but with good O2 exchange it isn't a problem. I am probably pushing the CO2 much higher than you need to(2bps), even 1bps is probably more than you need in a 10g(I'd start with 30bpm and check pH), the only major downside to 24/7 in nano tanks is that you waste CO2.

The trick is to have high surface area(not too deep tank, you are fine in a rectangular standard 10g), good surface agitation (lily pipe, skimmer).
I currently have a plastic tub with similar dimensions to my tank with no skimmer and it has been fine as well.

Quote:
Originally Posted by Bunsen Honeydew View Post
I think that this warrants more discussion, but I don't want to hijack LBL's thread more with this. If you don't mind, I will post another thread on the topic when I have a little more time to get into it. I haven't derived this one myself in awhile (since I was teaching this 15 years ago), so I probably should to compare to this chart and give it the proper rigor.
Beleive me I understand, I am a former Chemist(over a decade ago) I taught for 6+ years in the Generel Chemistry labs at McGill while working on my pHD, I was more than a bit rusty when I first started on this forum. A few month ago Tom Barr sophistry tripped me up and I referenced this chart when I first started posting here, I have learned not to ever reference this material in future and I think you will arrive at the same conclusions given your background and careful study.

IMO Barr is very good at simplifying down concepts for the masses but often the message is misleading or applied wrong by novices(like in this thread) and he rarely emphasizes caveats to his methods which is the problem with reading his material and following it or parroting blindly.

Last edited by Darkblade48; 05-14-2019 at 11:33 PM. Reason: Please use the edit function for back to back posts to keep threads cleaner
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Old 05-14-2019, 05:52 PM
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Quote:
Originally Posted by Bunsen Honeydew View Post
I think that this warrants more discussion, but I don't want to hijack LBL's thread more with this. If you don't mind, I will post another thread on the topic when I have a little more time to get into it. I haven't derived this one myself in awhile (since I was teaching this 15 years ago), so I probably should to compare to this chart and give it the proper rigor.

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Old 05-14-2019, 06:59 PM
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Quote:
Originally Posted by cl3537 View Post
Beleive me I understand, I am a former Chemist(over a decade ago) I taught for 6+ years in the Generel Chemistry labs at McGill while working on my pHD, I was more than a bit rusty when I first started on this forum. A few month ago Tom Barr sophistry tripped me up and I referenced this chart when I first started posting here, I have learned not to ever reference this material in future and I think you will arrive at the same conclusions given your background and careful study.

IMO Barr is very good at simplifying down concepts for the masses but often the message is misleading or applied wrong by novices(like in this thread) and he rarely emphasizes caveats to his methods which is the problem with reading his material and following it or parroting blindly.
Great, this should be great discussion. I too have a PhD in chemistry, so we should be able to get through some good stuff. I can't attest to how useful the chart itself is, but I do have some questions about your explanations. I look forward to digging through it, and even disagreeing, if we can do so without being disagreeable. I don't take these kind of things as gospel, but saying that they have no utility probably isn't accurate either. To effectively use a tool, we must understand what it tells us and and probably more importantly what it doesn't, IMO.

Quote:
Originally Posted by varanidguy View Post

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Sounds like a party.

“Science, my lad, is made up of mistakes, but they are mistakes which it is useful to make, because they lead little by little to the truth.” -Jules Verne
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Old 05-14-2019, 08:04 PM Thread Starter
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Quote:
Originally Posted by Bunsen Honeydew View Post
Great, this should be great discussion.
Sounds like a party.
I dont mind a hijack... Im sure people would appreciate a bit more discussion on the topic... I know I do! I would also be willing to do experiments... I have a masters in Science- bio side. So I am very interested. If we need a discussion, or a controlled experiment- I can assist

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Last edited by livebearerlove; 05-14-2019 at 08:19 PM. Reason: I am wiulling to be part of an experiment
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Old 05-15-2019, 01:47 PM Thread Starter
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Ok, UPDATE:
I need to turn the top about 1/2 a mm.... it is nearly impossible... if I go just slightly too far is blows up. then im reaching into the tank and trying to pull this thing out and the fish (and fry) get terrified. I want to upgrade to something else, this tiny metal button is a mess. Ill update in a few more days... but this is not sustainable unless I can leave it on 24/7

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Old 05-15-2019, 01:50 PM
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Quote:
Originally Posted by livebearerlove View Post
Ok, UPDATE:
I need to turn the top about 1/2 a mm.... it is nearly impossible... if I go just slightly too far is blows up. then im reaching into the tank and trying to pull this thing out and the fish (and fry) get terrified. I want to upgrade to something else, this tiny metal button is a mess. Ill update in a few more days... but this is not sustainable unless I can leave it on 24/7
That's why I recommended you take the diffuser out at night and leave it on 24/7 as opposed to shutting it off. It's very difficult to get the same setting over and over again.

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Old 05-15-2019, 02:16 PM Thread Starter
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Quote:
Originally Posted by Asteroid View Post
That's why I recommended you take the diffuser out at night and leave it on 24/7 as opposed to shutting it off. It's very difficult to get the same setting over and over again.
Now I understand where you were coming from. However; Doesnt it need to be at the bottom of the tank? then im washing my hands like crazy to remove medication from my hands, reaching into the bottom of the tank, bothering the fish or also adding a bubbler at night? correct me if im wrong.

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Old 05-15-2019, 04:50 PM
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Quote:
Originally Posted by livebearerlove View Post
Now I understand where you were coming from. However; Doesnt it need to be at the bottom of the tank? then im washing my hands like crazy to remove medication from my hands, reaching into the bottom of the tank, bothering the fish or also adding a bubbler at night? correct me if im wrong.
You could add an air stone that you run at night. That should be enough to offset the co2 and keep your fish from being harmed.

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Old 05-15-2019, 05:04 PM
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That's another way to go with the airstone, but still somewhat risky since the co2 will only drop based on how much surface agitation is created. It should be pretty simple to remove a small diffuser from an aquarium and put it back in. Your lost me with "remove medication from my hands"

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Old 05-15-2019, 05:20 PM
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To be honest, if you plan on running CO2 long term, you could solve these problems with a modest investment in a better quality system. It's a one time investment, and is more economical long term.

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Old 05-15-2019, 06:09 PM
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Quote:
Originally Posted by Bunsen Honeydew View Post
To be honest, if you plan on running CO2 long term, you could solve these problems with a modest investment in a better quality system. It's a one time investment, and is more economical long term.

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I second this sentiment but I had a hard time thinking of phrasing it without sounding like a jerk.

Bump:
Quote:
Originally Posted by Bunsen Honeydew View Post
To be honest, if you plan on running CO2 long term, you could solve these problems with a modest investment in a better quality system. It's a one time investment, and is more economical long term.

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I second this sentiment but I had a hard time thinking of phrasing it without sounding like a jerk.

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Old 05-15-2019, 06:52 PM
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I hope that I didn't sound like a jerk.. I don't even run CO2 and have never done more than diy, so I'm not a system snob.

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“Science, my lad, is made up of mistakes, but they are mistakes which it is useful to make, because they lead little by little to the truth.” -Jules Verne
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Old 05-15-2019, 07:21 PM
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Quote:
Originally Posted by Bunsen Honeydew View Post
I hope that I didn't sound like a jerk.. I don't even run CO2 and have never done more than diy, so I'm not a system snob.

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I don’t think you did! FWIW

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Old 05-15-2019, 07:54 PM
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I think OP knows he will upgrade long-term. Just trying to help with what he has now to make it usable and safe for the fish. Disposable systems are not at all cost-effective long term and are usually not very precise.

They do sometimes work in certain situations. I did have an 88 gram one on a 2 Gal tank that didn't have fish and each cylinder lasted around 3 months. I just left it on 24/7 and it held. Used it for well over a year.

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