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DIY Drop Checker

273505 Views 357 Replies 80 Participants Last post by  HeyPK
It is quite easy to make your own "Drop Checker" or CO2 Indicator from acrylic sheet. The object is to have a small device that holds a few ml of water/indicator solution under the water line of the tank, so there is an air gap between the tank water and the indicator solution water. The commercial versions of this range from the elegant ADA glass unit, which is currently out of stock, to a much cheaper imitation ADA glass unit from Hong Kong, to a Red Sea plastic unit which is still cheaper. All do the same job. Two of the commercial versions are the imiitation ADA unit:

and the Red Sea unit:

Both are available on ebay at: eBay: Type2 Co2 Drop Checker-monitoring proper dosage of CO2 (item 250038130859 end time Oct-18-06 09:05:18 PDT)
and eBay: CO2 Indicator Red Sea Real Time CO2 Monitor (item 300036151186 end time Oct-14-06 09:48:10 PDT)

The easiest way to DIY this is to use all straight lines and rectangles, and make it from acrylic plastic. I made one a couple of years ago, but hadn't figured out how to effectively use it so I tossed it. Here is what it looks like:

All of the pieces of acrylic have to have squared edges, and the pieces that establish the thickness of the device should be cut from a constant width strip. When glueing these together, remember, the assembly has to be air and water tight, and any smearing of the cement makes it hard to see the color of the indicator solution. For an indicator solution you can use the solution from an Aquarium Pharmaceuticals pH test kit, or any other test kit that gives yellow at pH=6 and blue at pH=7.2 - use at least double the number of drops of indicator solution as the kit says to use, to get a more intense color. (Using even 4X the recommended number of drops doesn't change the test reading, only the intensity of the color.) To use this see:
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So what are you doing to make the "solution" 4 dKH?

So you want the "solution" in the drop checker to be 4 dKH, then you add a pH regeant so that you can "see" the pH change in the solution as it is exposed to more or less CO2 that is diffused from the aquarium through the air gap and into the solution?

I must be missing something. 4 dKH and "green" (my test kit is pH 7 at green) would only be 12ppm. Where am I going wrong?

I'm probably fixing to order one of those drop checkers from eBay. Why not?
Yeah Hoppy, thanks! That is what I was fishing for in my last post. Wantplants asked in a better way than I.

Another Question

What is the difference between type 1 and type 2 on the knock off eBay drop checkers? It looks like the "bottom" bell is a different shape. Is it just an asthetic thing or is there a functional difference between the two? There is about $2 difference between them.

Also, I just noticed they have a different style yet. Look at this eBay: NEW!! Co2 Drop Checker-monitoring proper dosage of CO2 (item 250039658709 end time Oct-23-06 08:45:25 PDT)
I ordered mine a couple of nights ago, so I will have it up and running in a week or so hopefully.
Ok, that signature file got me intrigued. I think George Bush would classify that as "fuzzy math".

First, I have no idea where the 390.6 miles³ came from. Please help me out with that. Volume by definition is length x width x height. I see a width, I see a height, but I see no length. So how did we end up with 390.6 miles³ as a volume? And what is multiplied by what to yield 5.75 x 10¹³ ft³?? (390.6 x 5280³ = 2,062,368,000 ft³)

If we assume 5.75 x 10¹³ ft³ as the total cubic feet of the canyon, given an average width of 6 miles and given an average depth of .3 miles, the length would have to be 217.0169 miles.

As taken from the National Park Service and also listed at The National Park Foundation, the canyon is 277 river miles long, an average of 10 miles wide, and a maximum of 1 mile deep. Multiplied out, that is 4.07738327 x 10^14 ft³ or 81,547.67 ft³ per person. Given an 8 ft ceiling height, my new house in the Grand Canyon is 10,193 ft² (Sign me up!). Of course, I will have no yard and no roof above my flat 8ft high ceiling. I probably won't even be able to open my frond door due to the neighbor back wall being shoved up against my house. Oh well, you can't win them all!
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How long is the solution supposed to last in the drop checker? Does it "wear out"?
I still have my original batch in the drop checker. It has been in there for about 2 months now. I can glance in the aquarium and see the solution. If the solution looks blue, I know I'm out of CO2 (which has happened a couple of times). If the solution looks kinda clear (with the lights and background, etc., it looks clear), I know I have CO2 in the water.

When I do my weekly water changes, the water level falls below the drop checker. By the time I am filling my tank up again, the solution is bluish looking. It turns clear by the end of the day.
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