# Should my drop checker turn Blue over night?



## will5 (Sep 30, 2005)

I just setup my pressurized Co2 about two days ago and I have noticed that my drop checker turns blue over night. I have my Co2 on a timer. I am used to Diy co2 in which my drop checker was always green.

Thank you for the help.


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## fordtrannyman (Jan 17, 2008)

Are you using a certified 4DKH standard?
I run my Co2 24/7 so I can't answer from experience. But, in theory I would think that if you are using a timer then yes the permeability levels will drop overnight if co2 is not being injected. When the timer comes back on the levels will rise again, hopefully before the lights on.
Is it back in the green before lights on?


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## Lnb (Apr 15, 2008)

Co2 drop checker measures Co2. The 4dhk will change from basic blue color to green to yellow with the presence of Co2. It will change back to blue when there is no Co2.


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## NJAquaBarren (Sep 16, 2009)

Yees, drop checker is likely to change overnight if you shut off CO2 at night. If you run an air pump or have signficant surface agitation you will outgas even more CO2 over night. 

So yes, drop checker will change back toward blue as CO2 dimishes when your system is off. The more surface agitation you ahve, the more you will lose and it is very possible to go all the way back to original blue overnight.

If you have the flexibitily, start your CO2 30, or 60 minutes before lights on to get some CO2 back before the start of photosynthesis.


No real worries whatever you do, this is just about optimization, not a problem.

Gooo luck.


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## dr.tran (Oct 8, 2007)

Yes it does. But I leave mines on 24/7 now and I get better results. Just start of slow untill the fishes get used to it. Or if ur really worried about co2 poison, then have surface movement and u will be fine.


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## GTR (May 27, 2009)

I dug this up when i was going to start a similar thread.

My DC is more towards the yellow side by the end of the day. Come morning after the CO2 has been off for at least 10 hours it's still green with no sign of blue. If I take it out of the tank it will turn blue. Only one hole in a spray bar return breaking the surface. Tom surface skimmer on one of the XP3's.

All this CO2 and the plants grow like crazy but I can't grow a carpet plant and not have it get covered with BBA.

SteveU


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## bsmith (Jan 8, 2007)

If your fish and other livestock dont gasp, turn it up more. My co2 is on a timer with the lights and even during the day when its off the DC is still Yellow. roud:



GTR said:


> I dug this up when i was going to start a similar thread.
> 
> My DC is more towards the yellow side by the end of the day. Come morning after the CO2 has been off for at least 10 hours it's still green with no sign of blue. If I take it out of the tank it will turn blue. Only one hole in a spray bar return breaking the surface. Tom surface skimmer on one of the XP3's.
> 
> ...


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## GTR (May 27, 2009)

So then the DC is basically useless.


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## bsmith (Jan 8, 2007)

No its a great tool to get things dialed in but it isn't the end all be all. You could also get a 5-6-7Dkh solution that would turn green at different concentrations of co2. 



GTR said:


> So then the DC is basically useless.


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## OverStocked (May 26, 2007)

GTR said:


> So then the DC is basically useless.


This should really be a seperate topic, as co2 isn't the only thing that factors in growing a good carpet. How about yoru light? What lights do you have, how old are the bulbs, what k rating? What dosing do you do?


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## bsmith (Jan 8, 2007)

Since the OP has gotten the answer to his question. 

The fact that he gets BBA at the substrate would make one think he has plenty of light. Maybe not enough flow though. I used to have the same problem with my marselia minuta and sure enough if I cracked the bottle a bit the BBA would disappear.


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## GTR (May 27, 2009)

Really my question was answered. I should have left off the part about the BBA since that just muddied my real question. My thought was the DC was inaccurate since it wasn't turning back to blue once CO2 injection was off.

Back to the BBA just briefly, no way it's lack of flow. There's an elbow on one spray bar pointing directly where I've tried several carpeting plants. So much flow the substrate is almost blown away.

I'll try mixing up a batch of either 5-6-7 dKH solution, maybe 6. I'd mixed 4 dKH myself before I purchased some and they both worked the same. It's pretty easy and quadrupling the sample for testing may bring accurate enough results for our purpose. Is there information somewhere that shows the CO2 concentration and color change for the various solutions?

Thanks
SteveU


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## OverStocked (May 26, 2007)

GTR said:


> Really my question was answered. I should have left off the part about the BBA since that just muddied my real question. My thought was the DC was inaccurate since it wasn't turning back to blue once CO2 injection was off.
> 
> Back to the BBA just briefly, no way it's lack of flow. There's an elbow on one spray bar pointing directly where I've tried several carpeting plants. So much flow the substrate is almost blown away.
> 
> ...


It is all relative to the Ph/kh/co2 chart

http://csd.net/~cgadd/aqua/art_plant_co2chart.htm
http://www.thekrib.com/Plants/CO2/kh-ph-co2-chart.html

Your drop checker gives you a fixed kH. Then the co2 causes a change in the pH of the solution in the drop checker, causing the brom blue to change color. So you use the standard pH indicator chart(can't print one, need the one that comes with a bottle of pH reagent, as your monitor and printer will vary from what was original) that came. Using the pH chart from the brom blue will tell you where you fall on the chart using the new kH.


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## GTR (May 27, 2009)

Sorry I didn't mean what I said. Not a color chart. It's stated that 4 dKH turns to green at a certain CO2 level. Changing to 6dKH would mean it would take a higher CO2 concentration for the change.

What would those levels be for the 4-5-6-7 dKH solutions. I know these are all estimates but it's all we have to work with.

SteveU


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## OverStocked (May 26, 2007)

What I said explains it. You need to use the pH test kit color chart to show you what color will mean what, relative to the charts linked.


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## GTR (May 27, 2009)

Well once I did some more searching I could find that the DC will turn green at 6.6 pH when using 4dKH.
Without that the charts or calculator didn't do much.

From that it shows me it will turn green if I have...
4dKH = 30.143 ppm CO2
5dKH = 37.678 ppm CO2
6dKH = 45.214 ppm CO2

The problem is once it turns yellow you don't really know how far you've gone past yellow.

SteveU


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## OverStocked (May 26, 2007)

GTR said:


> Well once I did some more searching I could find that the DC will turn green at 6.6 pH when using 4dKH.
> Without that the charts or calculator didn't do much.
> 
> From that it shows me it will turn green if I have...
> ...


THe point of upping your solution to 5 or 6 dKH is to make it so you are trying to achieve green, not yellow.


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