# Why does my drop checker stay green all the time?



## Stasiu (Sep 9, 2007)

I've been trying to get my co2 dialed in and notice once my DC turns green - yellow, it stays that way. I have plenty of flow in the tank and run a bubble wall at night...why does in not change change back to a color that would indicate a decrease in ppm of co2 early in the morning when the co2 has been of for 8 - 10 hours. I recently have had is stay yellow for a couple of days after I over did it a bit on the co2. It's important to me because I'm using it to figure out what pH to set my co2 controller at.

I'm having problems with my controller injecting too much co2 and stressing my fish and killing some shrimp after water changes. Something in my tank is dropping the pH of the water before co2 injection and prevents me from directly measuring the pH of the water to correlate co2 levels. I know aquasoil and wood can drop ph artificially. My KH is 2 and the pH has measured as low as 5.0 with no signs of stress, and recently I've killed some shrimp with a reading of 5.4 the day after a water change. I've calibrated and rechecked my controller using 7 and 4 ph standards often throughout this process and it seems to be working correctly.


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## Hoppy (Dec 24, 2005)

Be sure to use a standard 4dKH water solution in the drop checker. That has to contain nothing but bicarbonate of soda, sodium bicarbonate, mixed with distilled water. Don't use tank or tap water. And, if you are using the indicator solution that came from one of the vendors in Asia, I suggest you use API pH test reagent instead.


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## Stasiu (Sep 9, 2007)

I'm using 4dK solution I made using R/O water and baking soda, should I still consider buying a commercial brand? I double checked it using an API KH test kit, and I'm using bromothymol blue from a Hagen nutrafin test kit.


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## Hoppy (Dec 24, 2005)

I'm not sure that RO water will work well enough. RO/DI water should work ok. You can buy a gallon of distilled water from most grocery stores, in plastic jugs, for about a dollar. Of course you are then just taking the word of the "manufacturer" that the water really is distilled.


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## Abrium (Jan 7, 2011)

I have the same issue. I have tried a 4 dkh standard using both RO water and distilled water. I made both using sodium bicarbonate. However, regardless of the type of water I use my DC still does not change. This leads me to ask two questions:

1. Should I just use my tank's water like the instructions stated to do anyway? 

2. Is this an issue with the cuttlebone I'm using to keep my pH above neutral? I use cuttlebone pieces in my filter to ensure that my pH is at least nuetral for my snails' shells. Is this throwing my DC off and if it is what can I do to make this device effective??

Thanks again, I love the experience and knowledge that can be gained from this forum. You guys have saved me one more than 1 occasion.


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## Abrium (Jan 7, 2011)

Wait a minute. Could someone possibly explain the validity of this information or possibly produce a work around? I pulled this information from here and it states:



> The pH-KH-CO2 Relationship: pH, KH, and CO2 have a fixed relationship as long as carbonate is the only buffer present (no phosphate buffers like pH-UP and- DOWN, Discus Buffer, etc). There are some parts of the country that have high levels of phosphates in their water supply. For those cases, determining CO2 levels will be difficult, as the phosphate will throw off the pH-KH-CO2 relationship, which means the CO2 charts and calculator below won't work. Note that the commercially available CO2 test kits will also be invalidated by the phosphates.


Transitively this would mean that if you have fish there is no way of even ball parking co2 levels if you have a tank whose bioload impacts calculations. I'm basing this information on the fact that all of the fish food that I have checked has a recordable amount of phosphorus. Can anyone comment on this? This has really got my wheels turning.


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## skerzfan (Dec 16, 2007)

That's why you use a 'pure' distilled water, bicarbonate solution instead of tank water. You are using this for your measurement and the status of your tank water doesn't matter. You're using a drop checker not the chart.


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## Abrium (Jan 7, 2011)

So your saying that I shouldn't even worry about any calcium bicarbonate buffer that I may be using in the tank water because the co2 gas exchange is happening as co2 dissapates from the tank and into the DC which houses a pure standard? 

That still has me wondering why my DC doesn't change color. I mean how am I suppose to use the DC as an at-a-glance tool if it never changes color...?

That makes me wonder about the co2 burn off rate. I mean surely it can't be staying in my tank all night. I don't think there should be a reading 14 hours later if no co2 has been running.


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## Dave-H (Jul 29, 2010)

I also have a hard time dialing in my CO2. My drop checker is emerald green, my ph controller says 5.8. The fish are happy but the plants aren't that excited. If I didn't have the ph controller, I'd probably just bump up the CO2 even higher but the ph seems like it might get too low. 

So, I slowly move the controller down about .1 ph every few days. So far, fish are fine and plants are slowly getting happier.


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## OverStocked (May 26, 2007)

Abrium said:


> So your saying that I shouldn't even worry about any calcium bicarbonate buffer that I may be using in the tank water because the co2 gas exchange is happening as co2 dissapates from the tank and into the DC which houses a pure standard?
> 
> That still has me wondering why my DC doesn't change color. I mean how am I suppose to use the DC as an at-a-glance tool if it never changes color...?
> 
> That makes me wonder about the co2 burn off rate. I mean surely it can't be staying in my tank all night. I don't think there should be a reading 14 hours later if no co2 has been running.


Your drop checker isn't changing because co2 is not changing. It Sure can stay in the tank all night. Mine does. Remember that they react slow, too.

Take the drop checker out of the tank, does it turn blue? 

The kh/gh/ph of your tank do not matter. What matters is that the drop checker offers GAS exchange and then reacts. It isn't based on any of the tank parameters other than gas, particularly co2. Your ph could be 3 and you could still have a blue drop checker.


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## Abrium (Jan 7, 2011)

You following me OS? hehe 

I also meant the co2 staying in the tank all night. You mean the co2 won't burn completely off in 14 hours?? That just seems hard to believe.


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## genomer (Mar 29, 2011)

Abrium said:


> You following me OS? hehe
> 
> I also meant the co2 staying in the tank all night. You mean the co2 won't burn completely off in 14 hours?? That just seems hard to believe.


Drop checkers take a considerable length of time to revert to their original hue when submerged. Your DC won't change back to blue overnight even with the CO2 completely off; this is a fact. As OS stated-take it out of the tank...it will turn blue within half an hour or so (as one would expect...atmospheric gas levels); you may then reinstall it. I'd change the solution, though. 

I wouldn't rely on the DC as your guide to all things CO2. Observation first, drop checkers/CO2-KH cross reference charts second.


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## mcubed45 (Jun 30, 2010)

my guess would be bad fluid. just buy some solution for a couple dollars. one less thing to worry about.


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## Abrium (Jan 7, 2011)

I'm testing it right now its been out of the tank for roughly 20 to 30 minutes and is changing color. I'm going to see if it goes back to the royal blue color.


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## West1 (Feb 28, 2011)

I had the same "green drop checker" with 4dkh/API ph test n didn't know why my DC was forever green after the first day of set up. I took it out twice and set it up again thinking it was me or the way I mixed it.

I added air stones that turn on at midnight and turn off at 6am and by the time 4pm hits, my drop checker is blue awaiting the Co2. I've checked my DC as early as 7:30am and have seen it blue every time. Maybe this is an option for you?


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## mcubed45 (Jun 30, 2010)

West1 said:


> I had the same "green drop checker" with 4dkh/API ph test n didn't know why my DC was forever green after the first day of set up. I took it out twice and set it up again thinking it was me or the way I mixed it.
> 
> I added air stones that turn on at midnight and turn off at 6am and by the time 4pm hits, my drop checker is blue awaiting the Co2. I've checked my DC as early as 7:30am and have seen it blue every time. Maybe this is an option for you?


any particular reason you're lowering your co2 levels at nite? just makes it take that much longer to raise it again and wastes more co2.


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## West1 (Feb 28, 2011)

mcubed45 said:


> any particular reason you're lowering your co2 levels at nite? just makes it take that much longer to raise it again and wastes more co2.


 
I have fish in my tank and try to give the best for both plant/fish worlds. it might waste more Co2 but as long as the more pricey stock is happy, im happy to refil a 10-15.00 bottle of Co2:smile:.


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## mordalphus (Jun 23, 2010)

I was under the assumption that co2 levels at night don't effect livestock as long as there is also dissolved oxygen in the tank. And as long as your plants are healthy, there should be a high amount of dissolved oxygen in your water from photosynthesis! I've never had a problem with my fish struggling at night, they react the same whether or not there is co2 in the tank.

After all, you are running gas during lights on, and keeping the co2 levels higher than the plants are using (if your drop checker is green), so what's the difference between day and night? as long as you're not injecting MORE co2 during night time, there's no reason to outgas all of the precious carbon!


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## West1 (Feb 28, 2011)

Well... Goes to show how new I am at Planted Tanks. I was lead to believe o2 at night was good. Not sure if I read it on a sticky, read it on a replied PM or where but I remember reading it was good to do so. If it's false information, I apologize 
I'm guessing it was a PM since it sounds like o2 is not a good idea at night.


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## mordalphus (Jun 23, 2010)

Well ya gotta do what you gotta do to feel that your fish are safe, I understand that! But oxygen and co2 co-exist in the water column, it's not one or the other, so even though your drop checker is green, it doesn't mean there is a diminished level of oxygen in the tank, it just means there's a safe level of co2 in the tank.

If your co2 stays ON all night, you might want to have some aeration, or install a timer on your solenoid. Only because plants would stop using the co2 when there's no light, and levels would go higher than during the day.

I used to use an airstone at night, but found no change in fish health or activity when I removed the airstones, just healthier, lush plants!


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