# what co2 drop checker should i get?



## PlantedRich (Jul 21, 2010)

The drop checker is a pretty simple thing so most of them do work about the same with some really important points to watch. One is that what you put in them has to be right. We often read about trouble with the fluid used not being what it needs to be. That is a killer for both a $2 and a $20 drop checker. Beyond that, it is pretty much a personal choice appearance item. Get one that fits your price point and looks okay to you. It's quite possible you will want to hide it in a back corner anyway so I don't pay much for high appearance. They all look like an extra piece of equipment hook in the tank? My priority is to get good fluid and one that stays where I put it.


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## ryanperry875 (Oct 10, 2016)

ok, thanks. do you have a good fluid that you would recommend?


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## Nlewis (Dec 1, 2015)

4dkh fluid which you can buy or make yourself.


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## sevendust111 (Jul 15, 2014)

A member here nilocg used to sell them with a pre made solution on his eBay page. Maybe he still does.


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## Seattle_Aquarist (Jun 15, 2008)

ryanperry875 said:


> need help deciding which drop checker works best.


Hi ryanperry875,

Welcome to TPT!

Over the last several years I have used several drop checkers, the glass ones are fine but difficult to clean especially if algae starts to grow on the inside. My last purchase was Fluval CO2 Indicator Kit. There are several things I like about it: the white cone background makes it easy to distinguish the actual color; tt comes apart for easy cleaning; has a good suction cup; it comes with 4.0 dKH indicator solution; and sells for about $11 on Amazon and $12 on Ebay (with free shipping).


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## PlantedRich (Jul 21, 2010)

I'll double down on the Fluval recommendation. To me, it is simply a tool and if it works as well, I think look for ease of use and price.


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## houseofcards (Mar 21, 2009)

As the others have mentioned, a drop checker is a pretty simple device so it's pretty tough to go wrong other thank look or price. It should be noted in case you don't know if you make your own or buy 4DKH solution you still have to add a few drops of PH test solution to turn it blue. I think most come with what they call Co2 Indicator solution which is ready to go. 

I was looking for something small for my little nano and bought this one recently really cheap. It actully hangs on the outside of the tank which is perfect for my setup, plus will help with algae as well.


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## Hoppy (Dec 24, 2005)

houseofcards said:


> As the others have mentioned, a drop checker is a pretty simple device so it's pretty tough to go wrong other thank look or price. It should be noted in case you don't know if you make your own or buy 4DKH solution you still have to add a few drops of PH test solution to turn it blue. I think most come with what they call Co2 Indicator solution which is ready to go.
> 
> I was looking for something small for my little nano and bought this one recently really cheap. It actully hangs on the outside of the tank which is perfect for my setup, plus will help with algae as well.


I wouldn't use this one. It will be very slow responding to changes in CO2 concentration, because of the very small diameter of the air-water interface in the tank and the long passage to the drop checker fluid. Also, if your tank is warmer than the room air it will tend to distill water from the tank into the drop checker fluid chamber, making it less accurate.


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## houseofcards (Mar 21, 2009)

Hoppy said:


> I wouldn't use this one. It will be very slow responding to changes in CO2 concentration, because of the very small diameter of the air-water interface in the tank and the long passage to the drop checker fluid. Also, if your tank is warmer than the room air it will tend to distill water from the tank into the drop checker fluid chamber, making it less accurate.


Thanks for those words of caution. I have a more traditional drop checker a well. I think I'm going to put that in the tank right next to the external one and see what the response difference is. 

They sell external ones at GLA for about $40, this one was $7 so I fiqured I would take a chance since its on such as small tank.

Should also add the tank is room temp.


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