DIY Drop Checker - Page 3 - DIY Aquarium Projects

Gatorguy · 10-22-2006, 07:27 AM

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)

kamel_007 · 11-04-2006, 12:13 PM

Quote:

Originally Posted by hoppycalif

This works because a sealed container of air in contact with water will reach an equillibrium amount of CO2 that is at least proportional to the ppm of CO2 in the water. So, two containers with their water in contact with the same sealed container of air will reach the same ppm of CO2. The "drop checker" has distilled or DI water in it, with a known KH obtained with bicarbonate only - no other source of alkalinity, and no source of acidity. That makes the equation that is behind the pH/KH/CO2 table work correctly (see Chuck Gadd's website). So, if we can measure the pH of that little bit of water in the "drop checker", and we can, by using a pH indicator solution, we can accurately calculate how much CO2 is in that container of water, which will be the same as is in the tank water, since they are connected with a sealed air column. At KH=4, and 30 ppm of CO2, the pH will be 6.6 which turns the bromothymol blue indicator, used in almost all pH kits, green. So, green means you have the right amount of CO2 in the water, and yellow green means you have too much, while blue green means you have too little.

There is no way for the indicator solution to migrate to the tank water, since there is an air gap separating it from the tank water. If it did get into the tank water, it would be about 4-8 drops of a 4% sodium hydroxide in water solution with a little bit of bromothymol blue dye in it. It wouldn't be desirable to have it mixed into the tank, but I doubt it harming anything if it were mixed in.

So, to use this:
First, get some distilled water from the grocery store.
Using clean glass container, pour about a cup of that water into the container.
Next, add a very small amount of bicarbonate of soda - baking soda - Arm and Hammer soda, etc. to the water and stir it up with a very clean stirrer.
Test the KH of that water with your test kit.
Most likely it will be a higher than 4 KH. So, add some more distilled water and repeat the test. (If the first KH comes out to 8 degrees KH, double the amount of water. If it is 6 degrees of KH, add 50% more water, etc.)
When you get close to 4 degrees KH, repeat the test using twice as big a water sample in the vial as the kit calls for, then count each drop of KH reagent as being half the degrees of KH that the kit normally says - for AP test kit, that makes each drop equal to .5 degrees KH. I found I can get very near "exactly" 4 degrees KH by doing this carefully.
Use a syringe to squirt some of this 4 degrees KH water into the bulb of the "drop checker". Fill the bulb about 2/3 full of the water.
Add a few drops of your pH test reagent - use enough to get a strong blue color, but not so much that the water becomes opaque with the blue dye.
Use the suction cup on the "drop checker" to suspend the device two or three inches below the tank water surface, with the "horn" of the "drop checker" pointing down so it traps air in the horn.

After a couple of hours or so the color of the "drop checker" fluid will be at about the equillibrium color, and that should be green if you have 30 ppm of CO2 in the water. If the color is yellow, you have at least 70 ppm of CO2 (and your fish are in serious trouble!). If it is blue, you have about 10 ppm of CO2, which is not nearly enough.

is the color will be the same of PH test color??

and the water inside the DROP CHECKER with KH of 4.. i do add 7 drops of PH test.. and do i've to add KH test drops?

elaphe · 11-04-2006, 02:45 PM

You need to look at one of the pH/KH CO2 charts and figure out where you want your CO2 levels. At a KH of 4, and a pH at 6.6, you have 30ppm of CO2. At a KH of 5 (what I'm running) you have a CO2 of around 38 to 40ppm. The pH regent will be green at a pH of around 6.6.

You need to use pure water (RO/DI, distilled, etc) and add enough baking soda to get your water to whatever KH you want (this is the fun part - trust me, it doesn't take much baking soda). You then put this water in the drop checker and add a few drops of pH test regent. You want it dark, but not so dark that you can't see through it.

It will be BLUE when you first put it all together. After about 2 hours, you will see that it has changed. If green, your good. Yellow, to much CO2; still blue, not enough CO2.

I noticed in my ADA catalog, they say to use your aquarium water. This won't give you an accurate measurement because of other contaminates in the water. I guess it would give you some kind of idea?

Brian

hoppycalif · 11-04-2006, 03:57 PM

Quote:

Originally Posted by kamel_007

is the color will be the same of PH test color??

and the water inside the DROP CHECKER with KH of 4.. i do add 7 drops of PH test.. and do i've to add KH test drops?

The color will be the same as for the pH test kit, since that is what you are doing - measuring the pH of the bit of water in the bulb. It works because that water is "perfect" water for using the pH/KH/CO2 chart, unlike the tank water, which is far from "perfect". Don't add any KH test reagent to the bulb.

kamel_007 · 11-05-2006, 09:48 AM

Quote:

Originally Posted by hoppycalif

The color will be the same as for the pH test kit, since that is what you are doing - measuring the pH of the bit of water in the bulb. It works because that water is "perfect" water for using the pH/KH/CO2 chart, unlike the tank water, which is far from "perfect". Don't add any KH test reagent to the bulb.

OK.. im understand

SO i put 5 ml of water with KH of 4 and 7 drops of PH test.. as written in my PH test kit,

then.. i can't get this glass of drop checker.. it's not available in my country..

and till now.. i didn't find anything mach it.

could you help me?

hoppycalif · 11-05-2006, 10:20 AM

Quote:

Originally Posted by kamel_007

OK.. im understand

SO i put 5 ml of water with KH of 4 and 7 drops of PH test.. as written in my PH test kit,

then.. i can't get this glass of drop checker.. it's not available in my country..

and till now.. i didn't find anything mach it.

could you help me?

Page 1 of this thread shows one way to DIY one. Another way is to use clear plastic tubing, about a half inch in diameter. Bend a small "U" shape. Cement a plug in one end of the "U". Attach a suction cup to the side of the "U".

Another way to DIY one: Get a piece of one inch diameter clear plastic tube, about two inches long. Cement a disk of clear plastic on one end to seal it. Make another same size disk of clear plastic, except with a half inch diameter hole in the middle. Cement that on the other end. Get a piece of half inch diameter clear plastic tube, about one inch long. Cement it in the hole, with all of the tube sticking up into the big tube. All joints have to be water tight. Attach a suction cup to the side. Put the 4 dKH distilled water and reagent in the outside, big tube. Put it in the tank with the small tube opening facing down into the water.

I'm sure there are other ways to DIY one of these.

hoppycalif · 10-22-2006, 08:48 AM

Functionally, they have to all be the same. But, esthetically there is a difference. I think, from looking at the photos, the "type 1" is a more direct copy of the ADA unit, while the "type 2" is produced by a different glass blower, and less effort was put into matching the appearance of the ADA unit. The teardrop shaped one is still another glass blower's interpretation of the idea. It looks very good, but I doubt it having as fast a response to changes in tank water CO2, since it seems to have a much smaller tank water interface (no "horn" to increase the surface area of the tank water being interfaced.) That last one would be much easier to load with water and indicator solution, and might satisfy some people much more for that reason. It is pretty hard to get the water and indicator into the "type 1" verson, and nearly impossible without a syringe with a bent "needle".

What is encouraging about this is that apparently this fellow in Hong Kong is selling these well enough to branch out into other versions. Maybe our discussions involving ppm of CO2 in the water will become more meaningful as more people use these.

turbowagon · 10-24-2006, 01:25 PM

ok, that is officially the coolest invention ever. Definitely gonna order one! Thanks for the link!

- Joe

elaphe · 10-24-2006, 02:30 PM

I got mine installed and working. The hardest part was getting the RO/DI water to 4 dKH. I think I spent about 1 hour doing this (add baking soda, more baking soda, more water, etc...). It was a little difficult getting the water/indicator in until I realized that the old pipettes from Seachem Flourish bend right around that tight curve and squirt it right in the bulb.

It is a very cool device that gives you a good indication of the CO2 levels at a glance.

Thanks for being the guinea pig and trying this out for us

.

Brian

hoppycalif · 10-24-2006, 03:52 PM

Quote:

Originally Posted by elaphe

I got mine installed and working. The hardest part was getting the RO/DI water to 4 dKH. I think I spent about 1 hour doing this (add baking soda, more baking soda, more water, etc...). It was a little difficult getting the water/indicator in until I realized that the old pipettes from Seachem Flourish bend right around that tight curve and squirt it right in the bulb.

It is a very cool device that gives you a good indication of the CO2 levels at a glance.

Thanks for being the guinea pig and trying this out for us

.

Brian

Thank you for biting the bullet and trying it too. I am now running mine with 5dKH water in it, so green means about 40 ppm of CO2. After a week or so it is still doing just fine. Apparently 40 ppm does not bother the fish. I hope a lot of us start using this little gadget, so we can find any problems there might be with it.