# Can you have CO2 deficiency with green drop checker?



## Gilles (2 Sep 2014)

The more i read on this forum, the more i come to understand that in my current tank CO2 and flow are the only fractions i have yet to tune..

So this quote got me thinking;


ceg4048 said:


> In a high light CO2 enriched tank flow is King. Anything that interferes with flow throughput must be eradicated immediately.



Especially the last sentence of this part is what intrigues me. I think that the reason people advise to improve flow is to improve nutrient distribution (micro/macro/co2). So i lowered my pH from 6.4 to 6.2 and i started my Vortech MP40 again to improve flow in the tank (nutrient transport mode, at about 4% of the max capacity to prevent my plants from being washed out).. But how do you know that you have enough flow and/or CO2?

What if you already have a green drop checker (not lime green, but green) consisiting of commercially available drop checker fluid (meaning no DIY stuff). Would you still increase the CO2 levels by lowering the pH even more  to the point where it turns lime green or lime? Because i currently already have a pH of 6.2 which i don't want to lower any more...

So whats left? I could raise the KH, to say... 4dKH ?


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## ceg4048 (2 Sep 2014)

You're asking the wrong question.
What you should be asking is "Why is it a problem if my pH drops below 6.2 due to CO2?"



Gilles said:


> Would you still increase the CO2 levels by lowering the pH even more to the point where it turns lime green or lime?


Yes. This is fundamental.



Gilles said:


> So whats left?


Add more CO2.



Gilles said:


> I could raise the KH, to say... 4dKH ?


Which has zero effect on the CO2.

Cheers,


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## Edvet (2 Sep 2014)

Gilles said:


> pH of 6.2 which i don't want to lower any more...


 Don't worry about pH, realy, dont.......
If  you don't want to add more CO2, because you are asphyxiating your fish (not because of dropchecker colour) lower your light amount.
If you don't want to lower your light amount, you'll have to add more CO2, at lower KH values you could need a pH drop of 2 points to get adequate amounts of CO2 (again pending on the amount of light).


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## Gilles (2 Sep 2014)

My fish are currently fine, i am just worried that the amount of co2 i have to add is more if my kh is lower; or is that a mistake in thinking?

In other words, ignore ph, focus on a (freshly filled) drop checker?

makes me wonder if i should step away from pH controlled CO2 and go for continues CO2 during photo period using a needle valve and drop checker?


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## Edvet (2 Sep 2014)

At lower KH you acid reaction will be bigger (less buffered), so if you get enough CO2 in to the water the drop you will see is bigger, if you don't allow the drop to be big enough ( pH controllers will do this), you wont have enough CO2



Gilles said:


> go for continues CO2 during photo period using a needle valve and drop checker


 pH probe
 Yes, but use your controler to measure pH only, dont let it close the CO2, that's how i do it. I have a Sera controler, the pH probe is in my tank, but just to show me the pH value from my seat 15 feet away. I was more interested in the daily drop, then the actual measurement. I don't care if it's 6.9 or 6.3, as long as the drop was over 1 full point (1.3-1.4 in my case) from morning to lights on.


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## X3NiTH (2 Sep 2014)

I'm using two pH controllers at the moment in 0dKH water, only one of which has control over the co2. The one that has control has its cutoff threshold set to 0.2pH below my ideal injection pH of 5.2  (lime green drop checker and pearling plants) so my co2 injection is continuous. Both controllers are displaying different readings from each other (both are correctly calibrated) due to the low KH but they both appear to be consistent in their range of measurement, both will tell me if my injection rate is too high or too low and I can adjust accordingly, much quicker than if I relied on the dropchecker alone.

My plants are responding better to a continuous injection rate than having it controlled, when it's controlled the co2 levels fluctuate around the controllers variance of 0.09 below target for cutoff and 0.1pH over target for switch on. That doesn't seem much since the drop checker is lime green all day telling me my co2 is fine, however to put into perspective how much gas the plants will miss out on can be seen with a soda stream bottle lasting 4+ weeks on the controller and only 2+ weeks with continuous injection. 

I've thought about adding some KH back at some point but i don't see it making much more difference in how much gas I inject to how much more it will confuse my measurements.

The continuous injection is the most important part and the plants response to this has been vigorous growth compared to slow/no growth.


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## pepedopolous (2 Sep 2014)

What about if your drop checker is continuously yellow?

P


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## Julian (2 Sep 2014)

pepedopolous said:


> What about if your drop checker is continuously yellow?



Mine is like this as well, I put it down to not much surface agitation. What's yours like?


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## Gilles (2 Sep 2014)

Interesting... So, what should i aim for if i'd go for the continues flow of co2? Start 1 or 2 hours before photoperiod and make sure it is dropped 1 full point when lights go off? Should i start with green and end up yellow, or how can i tune the CO2 distribution when i don't have a pH pen to help me (ghehe feeling to much reliant on technique)


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## ceg4048 (2 Sep 2014)

Oh, I forgot to mention that CO2 application requires a special technique...that occasionally involves the use of numbers.
Instead of reinventing the wheel I usually refer folks to a thread like http://ukaps.org/forum/threads/melting-marsilea-hirsuta-staurogyne-repens.28996/
Follow the instructions there and report the values you're able to achieve.
You do not need a pH pen, although you should definitely get one because it makes life a little easier. There are plenty of pH test kit reagents such as the Bromo Blue you might be using in your dropchecker.

Cheers,


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## pepedopolous (2 Sep 2014)

Julian said:


> Mine is like this as well, I put it down to not much surface agitation. What's yours like?


I started to suspect my drop checker fluid but I've changed it recently and it went yellow again and stayed that way. 

The drop checker in my other aquarium (with fluid from the same bottle), doesn't go quite as yellow, but starts out each day green and then changes to yellow by lights on.

Yep, I think the second aquarium has more surface agitation. In the always-yellow one, I have a spraybar pointed straight ahead. In the other aquarium, there is a steel outlet pipe plus an Eheim Skim 350.


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## Gilles (3 Sep 2014)

Ceg; Thank you so much for your help. The day before yesterday i lowered the PH from 6.4 to 6.2 and yesterday the drop checker was still green so i lowered it to 6.0. With regards to Bromo Blue; I have a bottle of ADA drop checker fluid which basically says; add 1 drop and fill up with with aquarium water.

My PAR is around 60 and is measured using an Apogee meter on "Sun" mode it is about 5 lower on "electrical mode"; but i have LEDs and don't know which value to choose. Actually it bounces between ~58 and ~63 because of surface movement...


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## ceg4048 (3 Sep 2014)

Yes, and typical of The Matrix, those instruction are totally crap. You should never fill your DC with tank water, or any other water exacpt for distilled water adjusted to a known Carbonate Hardness. In any case, the so-called ADA dropchecker fluid is can't be anything else but standard Bromothymol Blue, which is used in nearly all pH reagent test kits around the world. 

Unfortunately, Bromo blue is not accurate below a pH of about 6. It turns yellow and stays yellow. If the alkalinity of your tank were higher then it would be useful because the pH levels would be above 6. So, the only choices you have are to either raise the alkalinity so you can get meaningful pH data or use a pH pen that is capable of reading somewhat accurately below a pH of 6. 

There are pH reagents that read below 6 but they are not commonly available so you'd have to get them from a lab.

Cheers,


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## Gilles (3 Sep 2014)

hehe just read your comment in this thread; http://ukaps.org/forum/threads/best-and-simplest-way-to-inject-co2.27268/page-2#post-284469


ceg4048 said:


> How long ago was it that DC vendors included instructions to use tank water to fill the DC? A totally inappropriate instruction, rendering an already poor tool even more pathetic.


Immediately i thought; "Hmm..."

So next question i have for you; I have a Fluval FX6 with 25mm inner diameter filter hose (the motor is at the bottom of the filter), i currently have CO2 injection using an bored out AM1000, although bored out, it is still nowhere near 25mm and has a few 90 degrees in it so the AM1000 most definately restricts flow. I also have 2x ADA pollen glass Beetle 50Ø for CO2. Why 2? Because i thought injecting co2 at 2 places would be better. Now i now better that i should inject CO2 in such a way that flow would cover the distribution of CO2; as in; only 1 place. Would you advise to:
1) Remove the AM1000 and switch to ceramic disc placed under filter intake (or)
2) Remove the AM1000 and switch to co2 tube in T to filter intake? e.g. no discs?
3) Together with (1) or (2); upgrade 1 outflow to a spraybar to even out the flow throughout the tank.



ceg4048 said:


> You should never fill your DC with tank water, or any other water exacpt for distilled water adjusted to a known Carbonate Hardness.


Which can also be interpreted as; "if you want it easy, go for something that is already mixed" ?; for example the Aqua Rebell CO2 Check fluid, which i already have at home but thought that ADA was maybe outperforming it e.g. better...



ceg4048 said:


> Unfortunately, Bromo blue is not accurate below a pH of about 6. It turns yellow and stays yellow. If the alkalinity of your tank were higher then it would be useful because the pH levels would be above 6. So, the only choices you have are to either raise the alkalinity so you can get meaningful pH data or use a pH pen that is capable of reading somewhat accurately below a pH of 6.


So let me get this straight, since i think i might be getting the hang of it...

Low alkalinity means a faster pH drop due to the added CO2 gasses but also makes your drop checker worthless to tell how much CO2 you really have. Not due to the low alkalinity, but due to the pH dropping below 6.
Low or high alkalinity means nothing; you still have to add thesame amount of CO2 gas to get a certain CO2 concentration in your tank; for instance 30ppm CO2 (i know you hate the number) would need the same amount of gass in low alkalinity as in high alkalinity.
Is there any alkalinity know at which CO2 drop checkers are usefull? I tend to go no higher then 4dKH because i want to have more difficult plants. Or just skip the drop checker altogether, only use the pH pen to monitor and look at the fish and plants...


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## ceg4048 (3 Sep 2014)

Gilles said:


> Low alkalinity means a faster pH drop due to the added CO2


Yes this is true.



Gilles said:


> but also makes your drop checker worthless to tell how much CO2 you really have. Not due to the low alkalinity, but due to the pH dropping below 6.


Not really because the dropchecker does not have to have a low alkalinity. You can add whatever level of carbonate to the DC water in order to raise the true KH of the sample water. We just use a standard 4dKH because we want to keep the color band simple with easy correlation to the CO2 concentration level. As long as the water in the DC is distilled or RO and as long as the KH in that water is adjusted ONLY with a carbonate/bicarbonate addition then the relationship in the pH/KH/CO2 charts will be valid in the checker.

But we are not talking about the usefulness of pH reagents in terms of the DC. You have confused this. 
We are talking about direct pH measurements of the tank water in order to determine the rate of dissolution in the tank. The DC cannot be relied upon to perform the pH profile check. Only direct pH measurement of the tank water can do that. That can only be accomplished if using bromo blue when the alkalinity is high enough so that the pH does not fall below the ability of bromo blue to register a valid pH value.

I would always choose to use a pH probe or pH pen type meter, simply for ease of use, however they also require repetitive calibration and they also have reduced reliability at low alkalinity.

Just for the sake of sanity it's really best if you just add some bicarbonate or carbonate salts to the tank at water change time to raise the alkalinity to useful values. This avoids confusion.



Gilles said:


> for example the Aqua Rebell CO2 Check fluid, which i already have at home but thought that ADA was maybe outperforming it e.g. better..


Please...




Gilles said:


> 1) Remove the AM1000 and switch to ceramic disc placed under filter intake (or)
> 2) Remove the AM1000 and switch to co2 tube in T to filter intake? e.g. no discs?


These are the better options. As you have discovered, even minor reduction in the tube diameter causes large reduction in flow. The problem with these options is you need a reliable way of getting as many of the bubbles to actually get sucked into the filter intake - but that's a better problem to have than having reduced flow rate, no question.

Cheers,


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## Edvet (3 Sep 2014)

Gilles said:


> only use the pH pen to monitor and look at the fish and plants


 
For the best way to dissolve CO2 I would always look at DIY homemade diffusors. Cheap and effective and can be made scaled to your tank (zillion plans on the interweb thingy).
Another good option is to get the CO2 in your cannister and have it dissolve there.


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## Gilles (3 Sep 2014)

ceg4048 said:


> Just for the sake of sanity it's really best if you just add some bicarbonate or carbonate salts to the tank at water change time to raise the alkalinity to useful values. This avoids confusion.


Define usefull; is a kH around 3 to 4 and gH around 6-8 usefull enough?



ceg4048 said:


> Please...


yep, ashamed.. got me 

What is the better option to get the CO2 into the tank? Adding a ceramic disc beneath the intake (micro bubbles, but cleaning) or adding a CO2 tube directly into the filter intake? I really think the size or rated performacnce of the disc does not matter; as long as it gets the job done in a timely fasion, right? I also have a twinstar, i might even add that below the filter intake


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## ceg4048 (3 Sep 2014)

Gilles said:


> Define usefull; is a kH around 3 to 4 and gH around 6-8 usefull enough?


Well, I'd suggest starting with a KH of 4. GH does not really matter for this purpose so it can be anything.
See what the pre-Gas-on pH is. If the value is in the lo 6's for example, and if you are only using a Bromo blue reagent to measure the pH profile then that won't be useful because you won't be able to measure below 6 and you'll need to be in the low 5's or mid 4's. 

If you'll use a pH meter which reads down to the low 4's then 4 KH is useful.




Gilles said:


> What is the better option to get the CO2 into the tank? Adding a ceramic disc beneath the intake (micro bubbles, but cleaning) or adding a CO2 tube directly into the filter intake?


You should experiment to find out. I cannot say unilaterally because filter performance, media content, bubble sizes all vary and all have an effect on the filters ability to dissolve the gas. Smaller bubbles from the disc is a head start. Sometimes, if luck is against you, the bubbles accumulate in the filter and you get noise, burping and spitting out of bubbles. Removing heavy filter media such as ceramic material helps to alleviate this problem.

Cheers,


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## Gilles (3 Sep 2014)

With Pre-gas-on pH you mean; the pH of the tank before i start injecting CO2. right? And i should make you a graph of the pH values during the day with my new non-ph-controlled CO2 setup for you to determine if i am on the right track?


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## ceg4048 (3 Sep 2014)

Yes, but you don't need to produce a chart, just report the time and pH in 30 minute intervals and indicate the time that the light goes on.
Perform the exercise on different days, one day using the disc and on another day with out the disc.

Cheers,


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## Gilles (3 Sep 2014)

check, will report back on saturday somewhere with some results.


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## Gilles (3 Sep 2014)

So i just finished with my first plumbing changes. I removed the AM1000 reactor and installed a ADA Pollen Glass 30mm below my Fluval FX6 filter intake.
Besides the fact that my Fluval does not resonate anymore because of the removed AM1000 (less noise, jay!) i also managed to remove 2x20mm 90 degrees elbows, with an inner diameter of 15mm (!!) This is currently replaced with silicone tubing with inner diameter of 19mm, so flow will improve a lot. CO2 is still on a PH controlled computer since i did not have time to do it all at once. Return flow will be replaced by original Fluval FX6 tubing which will be attached to a spraybar later on so i can remove my Eheim Skim 350.

Fluval is placed on a "resonation decreasing mat created from spare rubber tires" (originally created for washing machines) and it also helps a lot.






Air bubbles is due to the twinstar kicking in after an 80% water change which was long due, sorry for that...
Windows will be cleaned this weekend, this is 3 weeks of lack of window cleaning...









If you look at the last pic i might even be able to squeeze the ADA pollen thingy into the intake of the filter so no(!) co2 bubbles are waisted.


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## ceg4048 (4 Sep 2014)

Looks good so far. Do a pH profile check.

Cheers,


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