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C02 and ph controller
- Thread starter Rabbit229
- Start date
xim
Member
- Joined
- 19 Mar 2010
- Messages
- 499
No.
It works like a thermostat. But instead of controlling the temperature, this one controls CO2 injection.
CO2 makes water acidic and the pH gets down. So it uses the pH to determine when to inject or stop the CO2.
A pH controller kit has a pH probe that you put into the water, a controlling unit for you to set a
range of the pH, and an electric outlet for you to power the CO2 solenoid valve.
When the pH of the water gets down below the range you have set, the pH controller cuts the power of the outlet,
which will turn off (shut) the solenoid valve, stop the CO2.
Then when the CO2 level in the water gets depleted, the pH will go up. When the pH goes up above the set range, the controller will resume the power to the outlet. The solenoid valve will open and start CO2 injection again.
Have a look at the Level 3's diagram.
http://www.dennerle.eu/global/index...ategory&id=146&layout=blog&Itemid=206&lang=en
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5678
Member
Keen to see replies to this as I am interested in one too.
I'd be keen to hear peoples thoughts on the reliability of the PH controllers and their service requirements.
I'd be keen to hear peoples thoughts on the reliability of the PH controllers and their service requirements.
Basically they are an unnecessary toy that in most cases (there are a few expert people with gorgeous tanks and CO2 controllers) cause algae and sometimes fish death due to CO2 fluctuations.
The CO2 controllers do not in fact measure CO2 levels they measure pH, as with pure water (and carbonate buffered water) pH is related to the amount of CO2 dissolved. Unfortunately the pH reading of the pH probe in your tank depends on lots of other things other than CO2, hardness of water, amount of salts in water (especially true if dosing EI), amount of dead fish, amount of live fish etc. So off to a dodgy start here.
Also pH probes are not fit and forget devices, they do wear out and they really should be calibrated regularly. This is one reason CO2 controller users get algae as the probe drifts and CO2 levels drop, plants die and algae moves in.
Really a CO2 controller should measure a pH drop, they don't of course they measure absolute pH of the tank, as a pH drop of 1 unit from no CO2 to CO2 injected is about 30ppm regardless of the hardness of the water and in most cases water contamination. So you should really set you CO2 controller every day when CO2 and lights are off. If water is initially say pH 6.4 your need to set it to turn off CO2 at pH 7.4, which will be 30ppm CO2. Done.
Or, not use a CO2 controller, use timer on CO2 solenoid, drop checker to read CO2 level (or pH pen), slight surface agitation and just get on with it, like most of the people here manage to do.
The CO2 controllers do not in fact measure CO2 levels they measure pH, as with pure water (and carbonate buffered water) pH is related to the amount of CO2 dissolved. Unfortunately the pH reading of the pH probe in your tank depends on lots of other things other than CO2, hardness of water, amount of salts in water (especially true if dosing EI), amount of dead fish, amount of live fish etc. So off to a dodgy start here.
Also pH probes are not fit and forget devices, they do wear out and they really should be calibrated regularly. This is one reason CO2 controller users get algae as the probe drifts and CO2 levels drop, plants die and algae moves in.
Really a CO2 controller should measure a pH drop, they don't of course they measure absolute pH of the tank, as a pH drop of 1 unit from no CO2 to CO2 injected is about 30ppm regardless of the hardness of the water and in most cases water contamination. So you should really set you CO2 controller every day when CO2 and lights are off. If water is initially say pH 6.4 your need to set it to turn off CO2 at pH 7.4, which will be 30ppm CO2. Done.
Or, not use a CO2 controller, use timer on CO2 solenoid, drop checker to read CO2 level (or pH pen), slight surface agitation and just get on with it, like most of the people here manage to do.
zozo
Member
There are system providing an all in one as far as posible. That is PH controller and solenoid and or time clock combined. Where you connect the co2 hose to the unit i believe JBL and Denerle have those kind of systems. Looks nice and fancy works the same as constructing a system from seperate parts. That's just a personal preference and a matter of trusting the product.
The downsite from the all in one system is, (without taking the cost in consideration) if 1 component in the system fails you need to bring/send the whole unit to the repair shop. And as long it is gone you're only left with a co2 bottle, a regulator, a difuser and a wet finger DC to probe.
But you can also do it all in seperate parts and buy a controler which probes the PH and operates a conneccted solenoid which again is switched on and off with a timer switch..
Well known instrument manufacturers providing these units are Milwaukee, Hanna instruments and Wiepro, the first 2 i already know for over 30 years. I guess after producing products like that for such a long time, they know what they are doing by now. I've used a Hanna for a very long time, still got it and it is far over 15 years old and still works with a 8 years old probe. Now i'm using an old Milwaukee SMS122 of which i do not know how old it is but it is and it still works like a charme with the 8 years old Hanna probe. (But did order me a new probe anyway last week).
I have no clue about the quality from the aquarium brands provided all in one systems.. My preference goes to what i have very good experience with. Seperate components and good old fashion brands with straight forward products.
The downsite from the all in one system is, (without taking the cost in consideration) if 1 component in the system fails you need to bring/send the whole unit to the repair shop. And as long it is gone you're only left with a co2 bottle, a regulator, a difuser and a wet finger DC to probe.
But you can also do it all in seperate parts and buy a controler which probes the PH and operates a conneccted solenoid which again is switched on and off with a timer switch..
Well known instrument manufacturers providing these units are Milwaukee, Hanna instruments and Wiepro, the first 2 i already know for over 30 years. I guess after producing products like that for such a long time, they know what they are doing by now. I've used a Hanna for a very long time, still got it and it is far over 15 years old and still works with a 8 years old probe. Now i'm using an old Milwaukee SMS122 of which i do not know how old it is but it is and it still works like a charme with the 8 years old Hanna probe. (But did order me a new probe anyway last week).
I have no clue about the quality from the aquarium brands provided all in one systems.. My preference goes to what i have very good experience with. Seperate components and good old fashion brands with straight forward products.
Definately stay away from a ph controller if youre starting off. You can get one just to monitor pH but not to set it into "automatic mode" and control co2 levels. Big chance youll gas all your fish if you do. Basically the set points have to be changed with any variation in water (hardness), like at the time of a water change.
zozo
Member
What Jose says it's not a lay back product where you can leave it all to the automation. What ever you use to make life more easy, with a live aquarium you have to stay on top yourself and check and double check all the time and control your controllers and still need to know what you are doing.
In the first place all that controller stuff is developed for professional farmers to grow huge tomatos for the food industry and such. From there it blew over to the hobby aquatic plant keepers and the aquarium branche manufacturers want a piece of that cake too.
For growing letuce there are not many downsides with this your tomato gets bigger or not, thats it. When it comes to livestock, enough said for that above. I honestly have to say i never ever would buy something like that for over € 180, not worth it. If i didn't find it by chance 2nd hand for € 15 i never would have bought the toy.
Hence the looks of this over 15 year old Hanna PH checker, where co2 in the aquarium still was only for the real die hards and rare to find..
it's not a lay back product where you can leave it all to the automation. What ever you use to make life more easy, with a live aquarium you have to stay on top yourself and check and double check all the time and control your controllers and still need to know what you are doing. In the first place all that controller stuff is developed for professional farmers to grow huge tomatos for the food industry and such. From there it blew over to the hobby aquatic plant keepers and the aquarium branche manufacturers want a piece of that cake too.
For growing letuce there are not many downsides with this your tomato gets bigger or not, thats it. When it comes to livestock, enough said for that above. I honestly have to say i never ever would buy something like that for over € 180, not worth it. If i didn't find it by chance 2nd hand for € 15 i never would have bought the toy.
Hence the looks of this over 15 year old Hanna PH checker, where co2 in the aquarium still was only for the real die hards and rare to find..
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M
Marcel G
Guest
How can the pH reading depend on the hardness of water? Hardness is the amount of Ca(+2) and Mg(+2), whereas pH indicates the relative amount of H(+) and OH(-) ions.
What may in fact depend (to some extent) on the amount of some of the above mentioned ions (like phosphates), is not the pH but rather the alkalinity which we use to estimate the CO2 level.
Total alkalinity = [HCO3-] + 2[CO3--] + [B(OH)4-] + [OH-] + [SiO(OH)3-] + [MgOH+] + [H2PO4-] + 2[HPO4--] + 3[PO4---] + [CH3COO-] - [H+].
So from this equation you can see what affects the total alkalinity:
1) in a positive sense: bicarbonates (HCO3) and carbonates (CO3), hydroxides (OH), silicates (Si), humic substances (CH3COO), and different forms of phosphates (H2PO4, HPO4, PO4)
2) in a negative sense: hydrogen (H) ions
So adding phosphates, silicates or humic substances into the tank will cause an increase of alkalinity, while the addition of acids (like HCl, H2CO3 etc. with H+ ions) will decrease total alkalinity.
BUT don't overestimate the effect of these substances!
Clearly the biggest impact on the alkalinity have bicarbonates (HCO3), and at higher pH also carbonates (CO3) ... as at high pH part or most of the HCO3 changes to CO3.
Examples:
KH = 1°dH, PO4 = 3 ppm
If in the aquarium water with a temperature of 27°C, pH 6.4 and the PO4 content of ~3 ppm we measure total alkalinity of 0.357 mmol/ℓ (= 1°dKH), the share of bicarbonates in the water will be about 90%, i.e. the carbonate alkalinity will be 0.9°dKH.
KH = 5.9°dH, PO4 = 3 ppm
If in the aquarium water with a temperature of 27°C, pH 6.4 and the PO4 content of 3 ppm we measure total alkalinity of 2.096 mmol/ℓ (= 5.9°dKH), then the carbonate alkalinity comprise of about 95%, i.e. 2.0 mmol/ℓ (5.6°dKH).
KH = 3.9°dH, PO4 = 12 ppm
If in the aquarium water with a temperature of 27°C, pH 6.4 and the PO4 content of 12 ppm we measure total alkalinity of 1.378 mmol/ℓ (= 3.9°dKH), then the carbonate alkalinity comprise of about 73%, i.e. 1.0 mmol/ℓ (2.8°dKH).
PS: At higher alkalinity the share of bicarbonates will increase (and the effect of phosphates will proportionately decrease).
I don't suppose anyone of us uses 12 ppm of PO4 in his/her tank. Most EI people use 3 ppm of PO4 at most. So under "normal" EI circumstances you can assume that the phosphates effect is 10% in 1°dKH tank, and 5% in 6°dKH tank at most. In reality, most phosphates will "disapear" from your water in a few minutes or hours (whether they being uptaken by plants or get absorbed into the substrate). So the effect of phosphates on total alkalinity is more like in virtual reality realm. But in some tanks with inert substrate is can play some (small) role. With the humic substances it's a similar story.
Ive actually noticed something interesting (at least for me) in my tank lately. I normally get a "ph drop" of around 1.2 with approx 1BPS. A few days back I added a lot of H3PO4 (phosophoric acid) to tank taking the ph down from 8.2 to around 6.9. Now the interesting thing is that with the same BPS I now get around 0.6/0.7 ph drop. So "ph drop" is not affected by carbonates (its independant), but it might be affected by other substances in the water e.g acids and bases. Also I appreciate this is not typical in "normal tanks" as ardjuna says since people dont normally add this much acid to the water.
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It is pH reading in presence of carbonate hardness and CO2.
Below is one of the "standard" charts mapping hardness pH and CO2 levels. As you see pH depends on hardness (and CO2).
The problem I think is that hardness can mean many things. It can mean Gh, KH, etc. Ph doesnt depend on GH but it does depend on KH. You guys are both right.
M
Marcel G
Guest
If you want to make more chaos in the topic then continue to use misleading terms like "KH hardness".
I don't know how about UK, but here in the Czech Republic the term hardness is (or should be) strictly linked to Ca(+2) and Mg(+2) ions. What the above chart refers to is not hardness but carbonate alkalinity! The difficulty most people have to understand this topic is caused mainly by using misleading (wrong) terms. The above chart has nothing to do with any hardness, because it just shows (in graphical form) the relationship between different carbon form in water => CO2:HCO3:CO3. Under different pH the carbon changes its form. So if you want to know what amount of CO2 you have in your tank, you need to know at least two other parameters from the equation: 1) pH, 2) HCO3 (or CO3) content. Without this data you won't be able to calculate your CO2 level. But here lies the core problem => We are not able to find out the HCO3 concentration in water! Why? Because we have no specific test on HCO3 ions. So how do we solve this problem? We can find out the HCO3 concentration indirectly ... by measuring total alkalinity. As I already stated, most of the total alkalinity value is made by the HCO3/CO3 ions. So by knowing the total alkalinity value (measured by the "KH tests"), we consider it to be HCO3 concentration (althougth it's not true). So if you want to use the above chart for estimating the CO2 concentration in your tank, you should know all this!
zozo
Member
Lets throw a pie to the Germans.. They started it with the GH in DH = GesamtHärte in Deutsche Härte grad und und und also also also dann kam KH = KarbonatHärte verdamt auch noch mal in Deutsche Härte Grad. Now the sceintists still are battling who to blame for the PH the H stands for Hydrogen, some say the P stands for the German Potenz but then the H = misleading Because Hydrogen isn't realy used in German they say stricktly Wasserstoff and it isn't PW. So it must be French? Because the laboratory where PH was discovered was French speaking it must be puissance?.. Nonono others say.. It must be Pondus Hydrogenii but still we got Potentia Hydrogenii. Now what is it?
No wonder pastries are doing so well these days.. Don't they?
But i guess at the bottom line Marcel is right we also say Hard water when there is a lot of Calcium in it. Actualy not many poeple know it also can me Magnesium what they gor in the kettle..
They started it with the GH in DH = GesamtHärte in Deutsche Härte grad und und und also also also dann kam KH = KarbonatHärte verdamt auch noch mal in Deutsche Härte Grad. Now the sceintists still are battling who to blame for the PH the H stands for Hydrogen, some say the P stands for the German Potenz but then the H = misleading Because Hydrogen isn't realy used in German they say stricktly Wasserstoff and it isn't PW. So it must be French? Because the laboratory where PH was discovered was French speaking it must be puissance?.. Nonono others say.. It must be Pondus Hydrogenii but still we got Potentia Hydrogenii. Now what is it?No wonder pastries are doing so well these days.. Don't they?
But i guess at the bottom line Marcel is right we also say Hard water when there is a lot of Calcium in it. Actualy not many poeple know it also can me Magnesium what they gor in the kettle..
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DanielC03
Member
The tables reflect the Henderson-Hasselbalch equation. If you do not know all solutes we can not conclude anything
Rabbit229
Member
- Joined
- 18 Feb 2015
- Messages
- 263
This thread had just gone totally bonkers. I'm a newby and now I'm thinking to stay clear from aquascape and stick to my discus. It sounds to technical
I thought you could just get a system that is simple. I have no degree in water. I'm just a roofer
I thought you could just get a system that is simple. I have no degree in water. I'm just a roofer
M
Marcel G
Guest
I don't agree. If you know that HCO3 makes about 90% of the total alkalinity, and you measure 5°dKH, then the carbonate alkalinity (= HCO3 content) is 4.5°dKH, and this number you can use in the pH/alkalinity/CO2 chart. So although you may not know all the solutes in your solution, you can make a "qualified guess" ... in case you don't have any non-standard conditions in your tank. If you have lot of phosphates, lot of tanis or organics in your tank etc. ... then, of course, you are better not to use the chart for CO2 estimation.
M
Marcel G
Guest
Sorry for our technical discussion, but in case you want to use CO2 in your tank, you should know (at least) some basics. And these (the above discussed things) are just basics. Someone may say that you watch TV and may not know the technical aspect of its operation also, but when using CO2 you can kill all your critters in your tank, so you should have some knowledge of its behaviour and natural relations. And the main problem we discussed here was that it's hard to even know the real CO2 concentration in your tank, because we have no affordable way how to measure dissolved CO2 directly (as true CO2 meters costs more than $2000). So the only way for us is to guess it based on some inaccurate measurements of pH and total alkalinity, and complicated scientific calculations.
PS: If you want to know the real hard scientific data behind the pH/KH/CO2 chart, then you can go here, fill out the input data, and click on the "calculate" button. You'll see all the details of how the chart is being "created".
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