# DIY drop checker/ The Body Shop Style



## Fat Guy (Nov 19, 2003)

this may be a little pic heavy, but I was bored today and wanted to build my own DIY drop checker. So I used an old scented oil container, mixed up a batch of 4dKH and went to town. Here's some photos. My only concern is that the modified plastic tube is too small and will take a long time for the gas to change the color of the ph reagent. I'll wait till tomorrow to see what becomes of it. But since I've put it in, I haven't been noticing any real significant change in color. Could it be that even with the pressurized setup, I'm not pushing that much CO2 into the water? Will I have to kick it up a notch? stay tuned.....

Here's what I did:










took the plastic wrapping off, boiled it and scrubbed all the oil off of it.









removed the oil distributor, my idea being that I could use the small pin hole channel for the gas to travel up and into the basin.

















took some sun cure resin that I use to repair the dings on my surfboards and filled in a hole on the distributor. (this one comes with two channels. One that is positioned in the middle of the plastic, and another one that is positioned deeper and travels the length of the plastic shaft. If you happen to see one of these containers, twist off the top and look at the holes and you'll see what I mean. 
Here's what I used to seal the one hole so that I could create a basin.








Here's the section I filled in:








used a suction cup setup that you can get at your LFS that will fit around a 1"heater. Fit like a glove. Then stuck it to my window in my dining room...just for good measure.








You can see the plastic channel better here. 
got some distilled water








mixed in some baking soda and tested and tested and tested until I got roughly 4dKH-4.5dKH. Added .2ml 4dKH water with a baby dosing syringe and 4 drops of pH reagent.
Then carefully put it in my aquarium.
























finishing touches...









Now, the issue that I'm having is that the drop checker solution is still blue and does not look like it has changed. It's been roughly 3 hours. I'm about to hit the hay here and will revisit the project in the morning. I have another option that I can use, but I like the way that this looks compared to some other diy setups that I have seen. I may run the second one I made next to this one to see if the gas really is making its way up the chamber. I used .2ml 4.5dKH and 4 drops pH reagent for the solution. I moved the drop checker to the far left corner under the glass and cranked the filter up to move the bubbles around. so far so good. just wait...after running the pressurized for this long, I'm gonna be kicking myself a little if I find out that I need to add more....at least the fix is an easy one. Just open up the needle valve a little and see where that takes me. After all...it's only moss were dealing with here.

Thanks for looking, 

-el g


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## stripe157 (Jan 4, 2010)

I think the problem with the delayed response (if there is a response) is due to the super small surface area... Or more clearly, the interface between the gas in the DC and the water. Even with the relatively large interface area of normal DCs, it takes an hour or so for enough carbonate (?) to move into the gas phase (attempting to reach an equilibrium), and then to dissolve into the liquid phase of the checker solution. 
I think the response time would be proportional to the area of water exposed to the "air" in the DC.


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## Diana (Jan 14, 2010)

Probably the small tube the gas has to travel through. Can you make it any larger? 

Really nice way to do this! That little bottle looks good, IMO.


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## Fat Guy (Nov 19, 2003)

Thanks for your comments stripe157 and Diana. I was contemplating making the hole bigger. However, when I woke up:

Overnight Success!!


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## Strick (Apr 6, 2009)

Sweet! Definitely on the to-do list. Thanks!


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## thrak76 (Aug 3, 2009)

That looks great! 
A friend of mine made a similar DIY drop checker, but with a smaller vial. I believe it was an insulin vial, with the plastic cap from a syringe inserted into it. It had more surface area, and a larger opening. He made a couple for me, and it sure saved us a lot of money.
Nice job, again.


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## Fat Guy (Nov 19, 2003)

this still works like a charm. Probably gonna change the fluid at the end of the month.


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## tyler79durdan (Jan 23, 2010)

Looks good, I had the same problem with delay from a DIY checker I made from an old bubble counter, from my Milwaukee 957. Same problem was my passageway was too narrow and took forever to transfer gasses. Great idea though and it appears to be working!


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## Fat Guy (Nov 19, 2003)

tyler79durdan said:


> Looks good, I had the same problem with delay from a DIY checker I made from an old bubble counter, from my Milwaukee 957. Same problem was my passageway was too narrow and took forever to transfer gasses. Great idea though and it appears to be working!


thanks tyler79durdan. I was contemplating making the passageway hole bigger too. Maybe I'll tinker with it a little...but...if it ain't broke don't fix it right? best- el g.


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## Diana (Jan 14, 2010)

Such a slow responce may not be as helpful as having more current information. As slow as this responce time is, it suggests that some time during the night the CO2 was up that high. I think I would make a larger opening so the results are more current.


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## Fat Guy (Nov 19, 2003)

Diana said:


> Such a slow responce may not be as helpful as having more current information. As slow as this responce time is, it suggests that some time during the night the CO2 was up that high. I think I would make a larger opening so the results are more current.


I understand your thinking. This drop checker took about 6-7 hours to change color. That may be a little long. I'm not too worried about it now though. It's been 20 days since I've installed it and all systems are go in the tank. But it definitely would be beneficial to have a speedier response time. Now I'm beginning to wonder if the color in the drop checker now is actually the levels in the tank from 6-7 hours before. Or is the chamber at an equilibrium with the tank now? Anybody have any insight into that? I was for some reason under the impression that once it is submerged and the gas fills the chamber, than that chamber is at an equilibrium. I could be way wrong.

With this tank, I had been running a pressurized setup for months and measuring the levels with pH and KH. However, with the addition of some of the rocks, my GH began to fluctuate a little, so I needed a better way to check the levels in the tank. This, albeit a little slower, reaffirmed for me the amount of co2 I thought I had in the tank was agreeable with the flora and fauna. But I agree, I think making a larger passageway would lead to a quicker result time for this style of drop checker. I may tinker with it today. Just need to find the right tool to expand it.


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## Fat Guy (Nov 19, 2003)

If you can tell as of recently, I've had a lot of free time the past couple of days. And with the rain in NYC, I've been spending a lot of time working on the aquarium. I wasn't happy with the drop checker chamber so I decided to make it bigger, without making it over complicated. It was taking way too long to get readings with the drop checker and I felt like it was because the gas wasn't traveling very rapidly into the chamber with the reagent. So I removed the cap, and took half inch airline tubing, cut it to size, and fit it through the opening in the glass vial, filled the container with approximately 3ml dKH4/4.5 H2O, added 6 drops pH reagent, tested the seal, and placed it in the aquarium. It went a little something like this. 








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## stewardwildcat (Feb 24, 2010)

Looks fantastic I will be copying your design soon.


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## Fat Guy (Nov 19, 2003)

Success in just under 3 hours!!

The new modification works like a charm:








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## Fat Guy (Nov 19, 2003)

this new modification works so well.


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## theredben (Dec 28, 2008)

The problem with your method is that you do not know what your C02 level is. Correct me if I am wrong but your measurement of 4-4.5 sounds like you made up a batch of cabonate solution and measured it with a aquarium test kit. The KH level inside the drop checker is vitally important. You need to either buy proper drop checker solution, make your own using online instruction, or just accept the fact that your c02 level might be anywhere from just what you want, up to 10 ppm higher or lower.

On second thought, the most important part is that you co2 level stays constant, and I guess that this will accomplish that.


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## Hoppy (Dec 24, 2005)

By far the biggest inaccuracy of a drop checker is caused by the difficulty in judging the color of the solution - the pH of the solution. Because the ppm of CO2 is proportional to one over 10 raised to the pH power, small errors in judging the color make big errors in ppm of CO2. A 10% error in pH of the drop checker fluid can mean a CO2 ppm that is off by a factor of 4 - instead of 40 ppm you may have 10 ppm or 160 ppm. By contrast, the ppm of CO2 is directly proportional to the KH of the drop checker solution, so a 10% error in KH means only a 10% error in ppm of CO2 - instead of 40 ppm you may have 36 or 44 ppm. That's why you don't need great accuracy in your 4 dKH solution - anything between about 3.5 and 4.5 works equally well.

And, this is why you can't rely 100% on what the drop checker shows. It only lets you get in the right ballpark with the bubble rate. To get to the optimum bubble rate you have to slowly increase the bubble rate a little once a day and watch the fish for distress, and the plants for pearling, to get close to the optimum bubble rate. The reason for using the drop checker is to keep you from getting cold feet and running the CO2 so low you have only 5 ppm, because you think the fish are suffering, not enough to keep the plants growing at high light intensity. And, just using the pH/KH/ppm CO2 tables to get the CO2 ppm can cause you to have 5 ppm when the table says you have 50 ppm.


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## theredben (Dec 28, 2008)

My issue was not the fact that it was 4-4.5, rather it was that I think it was measured using a horribly inaccurate hobby grade test kit. 
That could turn that 4-4.5 into anything from 2-6.

Obviously we are just talking theoretically here because he has had this running for a month and it seems to be working for him.


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## Fat Guy (Nov 19, 2003)

Hoppy said:


> By far the biggest inaccuracy of a drop checker is caused by the difficulty in judging the color of the solution - the pH of the solution. Because the ppm of CO2 is proportional to one over 10 raised to the pH power, small errors in judging the color make big errors in ppm of CO2. A 10% error in pH of the drop checker fluid can mean a CO2 ppm that is off by a factor of 4 - instead of 40 ppm you may have 10 ppm or 160 ppm. By contrast, the ppm of CO2 is directly proportional to the KH of the drop checker solution, so a 10% error in KH means only a 10% error in ppm of CO2 - instead of 40 ppm you may have 36 or 44 ppm. That's why you don't need great accuracy in your 4 dKH solution - anything between about 3.5 and 4.5 works equally well.
> 
> And, this is why you can't rely 100% on what the drop checker shows. It only lets you get in the right ballpark with the bubble rate. To get to the optimum bubble rate you have to slowly increase the bubble rate a little once a day and watch the fish for distress, and the plants for pearling, to get close to the optimum bubble rate. The reason for using the drop checker is to keep you from getting cold feet and running the CO2 so low you have only 5 ppm, because you think the fish are suffering, not enough to keep the plants growing at high light intensity. And, just using the pH/KH/ppm CO2 tables to get the CO2 ppm can cause you to have 5 ppm when the table says you have 50 ppm.


I could not agree with you more, Hoppy, and thank you for assisting in a very detailed response. My main purpose for using the drop checker is to make sure I am getting an adequate amount of co2 in my tank because the ph/kh/ppm co2 table was not accurate for me due to the rocks that I have in my aquarium. So, this drop checker is used to reassure me that I am getting, again, adequate co2, and not being deceived by the readings on the ph/kh/ppm co2 table. 


theredben- thanks for your input and concern with my drop checker solution. I used a Red Sea solution test kit for KH because it was available to me over the counter at my lfs. It is hobby grade. I actually used Hoppy's method for prepping the solution with baking soda here Thanks Hoppy. 

I couldn't be happier with my setup as the plants are thriving, the fish are happy, the scape is working, and the drop checker works like a charm for a simple DIY addition to my hobby. 

Best,

-el g

here's a recent picture of the tank


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