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True, but that is the kicker, I think:

X-amount of change in pH......

PPM stays the same though.....and that's what we are after....

Provided I am finally seeing this correctly!

Question:

I have made a DIY Drop Checker. It is bulky and I will post pix shortly. RODI Water set to 5Kh---How Much/Many pH drops do I add? Does it Matter? Do I need to measure the solution going into the Drop Checker and add 3 drops/5ml (AP Test Kit)?

Thanx!
 

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Discussion Starter · #142 ·
I experimented with the AP test kit, adding varying amounts of the pH reagent to tubes with the same water - tank water - in them. It made no difference to the results whether I used the three drops the instructions call for, or 2 or 6 or even 9 drops. With larger numbers of drops the result becomes a murky opaque liquid, where reading the color is harder, not easier. But, the color stayed the same for all. So, I just add whatever amount makes it easiest to judge the color.
 

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Hi Hoppy,

Thanx for the Clarification. I found the answer from some previous posts of Your's here:

DIY Drop Checker--Post #1

Which leads to here--More in-depth:

Does it work? ADA glass dropcheck co2 indicator--Post #25

Here's some Pix of the 1 I just made--Mind you, its cost was $0 (I had everything) and it's going into my A. javanicus setup--so, looks are not currently of utmost importance:

Parts:



Assembled--the top heater holder just goes above the bottle to help reduce the buoyancy-pull on the heater holder around the bottle neck:



Full:



Its an 8.45 Fl oz. "Kid's Connection Soda" bottle. I bought them at Walmart in a 4-pak for $1-2 and I use them for DIY C02 Bubble Counters. This one was an Extra. The PVC is just 1/2" and the bottle opening fits it like a glove--No glue, silicone, etc. It currently has about 95ml of RODI water set to 5kh w/ BS.

I added 114 drops of pH liquid--and its really too dark. I am going to install it an see how it looks under the light. But I will probably redo it with less drops. The water color is not Blue, but Blue-green--what does that mean? The RODI water was made yesterday and was putting out 0-2ppm TDS. The Gallon jug has just be sitting capped overnight. Any thoughts on that?

EDIT: I was afraid that the bottle body was just going to be too wide for the suction cup to hold--and it is. So, I have eliminated the suction-cups and tied 2--1 1/2 oz lead weights around the neck--dangling about 3" below the bottle. So, now it is a floating version. :-\"

Anybody know if the entire Drop Checker Must be below the water surface--like for pressure? I guess we'll find out in a few hrs!

I also redid the fluid mixture: 100ml and 10 drops of pH liquid. Now its a nice pretty blue and should be easy to read....

Thanx!
 

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Discussion Starter · #144 ·
The reason for keeping the entire device under water is to avoid any temperature difference between the device and the tank water. If there is a difference some distillation will occur - water will migrate from the warmer to the cooler area, which changes the KH of the tester water.

Are you sure there is no leakage between the pvc tube and the bottle neck? If so, that has to be the easiest one yet to make. (But not the most unobtrusive or most elegant or coolest!)
 

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Are you sure there is no leakage between the pvc tube and the bottle neck?
Absolutely? Positively? Well, No, but as You can see in the pic above--there is no leakage onto the Towel. And in order to get the PVC pipe back out--I have to insert my finger, bend it to kind of Lock it in place, and fight and struggle for a bit. I can't guarantee that there will not be any osmosis at all, but its a solid fit. Time will tell, I guess!

I just got the fishing line back out and tied it to a rock that will reach the bottom yet keep the Checker below the surface. Its in my Plant Filter, so looks really isn't a Big Deal. Ghetto? Yes, but if it provides some benefit--I'll do it right later...After 4hrs of floating--the color didn't change at all (floating). According to the Chart: I have pH 6.0, Kh 2, so C02 should be around 60ppm. We'll see if the color changes now that its completely submerged.

Thanx!
 

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Just a thought, but if the membrane idea pans out, these could be made even easier by gluing a piece of membrane to the top of any small clear container filled with indicator solution.

Like this:



It wouldn't matter which way was up since water can't go through the membrane and you could use any small clear container you have lying around with virtually no modifications. Heck, you could just glue membrane to either side of a piece of air line tubing. Then if it starts going bad, toss it out and throw a new one in.
 

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Discussion Starter · #147 · (Edited)
Just a thought, but if the membrane idea pans out, these could be made even easier by gluing a piece of membrane to the top of any small clear container filled with indicator solution.

Like this:



It wouldn't matter which way was up since water can't go through the membrane and you could use any small clear container you have lying around with virtually no modifications. Heck, you could just glue membrane to either side of a piece of air line tubing. Then if it starts going bad, toss it out and throw a new one in.
As I recall, the membranes are made of teflon or polypropylene plastic, and neither of those is at all easy to glue. Both are, I think, considered "release agents". If you can use glue, I hope someone with the knowledge will tell us which glue to use. If I had some membrane, other than Tyvek, which is very thick and stiff for something like this, I would just wrap it around a piece of tubing and rubber band it in place. I do have a pretty nice piece of transparent vinyl 1/2 inch tubing I could easily use this way. But, the first steps are to find a source of membrane, and to find out if there is a glue that will work with it.

EDIT: I did some googling and found the obvious source of membrane material - Kordon breather bags! Who has some and is willing to supply one or two to me - of course I will pay shipping and cost of the bag(s)?

EDIT AGAIN: It only took a few minutes to get two offers of these bags, and both are relatively local to me! If I can make this work out I will make two or three extras and offer them to whomever wants them. But, I hope someone else tries this idea too.
 

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EDIT: I did some googling and found the obvious source of membrane material - Kordon breather bags! Who has some and is willing to supply one or two to me - of course I will pay shipping and cost of the bag(s)?
Naja002 suggested breather bags already: http://www.aquaticplantcentral.com/...checker-14.html?highlight=breather#post256349

=P

I think, for an effective drop checker using a semi-permeable membrane, you could overfill a test tube or container or whatever, and place the membrane over the top so that there is absolutely no air inside the container. This way, the dissolved CO2 within the tank can directly dissolve through to the other side and give faster results.

Of course, since CO2 in H2O yields carbonic acid, I wonder if these molecules will be able to get through the membrane...no time to ponder this for now. Final exam in 2 hours. ;)
 

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The Breather bags are designed to let C02 out and 02 in--question is: does it go both ways?

In order to maintain equilibrium the C02 must be able to enter and exit as it changes in the tank. Guess that would be a question for Kordon.

My Ghetto Drop Checker changed colors since I completely submerged it. Its Green now, but hard to tell Which Green! :rolleyes: I guess I'll add a few more drops of the pH liquid and see if that helps.....
 

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Discussion Starter · #150 ·
The reason the Kordon bags "let oxygen in and CO2 out" is the same reason it will work for the drop checker. The gas will always reach equilibrium conditions on each side of the membrane. So, if the fish or plants are using O2, the O2 concentration will drop on that side of the membrane and O2 will have a net inflow to that side. But, if the fish or plants release CO2, the CO2 concentration will increase on that side and there will be a net outflow of CO2. The membrane is little more than a net with extremely small openings, so it must be able to let gases go either direction.

If I were designing a membrane drop checker for sale, I would have a sheet of membrane with 4-5dKH water and pH reagent spread on it, lay a second sheet on top, then heat seal a grid of 1" squares, so it separates into a bunch of 1" square pillows with standard KH water/reagent sealed inside. One of these could just float in the aquarium - it would have near neutral buoyancy.

So, who has a machine that does this - seals two heat sealable plastic sheets together in 1" squares? Surely one of us has one hidden away in the garage??
 

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Makes sense. I just never really thought about it. The description that I read--probably a yr ago--basically said that it let's C02 Out and 02 in because of the pore size. But I guess what they were really getting at is: because the the pore size--it allows the gas exchange while keeping the Water in!

If I were designing a membrane drop checker for sale, I would have a sheet of membrane with 4-5dKH water and pH reagent spread on it, lay a second sheet on top, then heat seal a grid of 1" squares, so it separates into a bunch of 1" square pillows with standard KH water/reagent sealed inside. One of these could just float in the aquarium - it would have near neutral buoyancy.
Sounds like a New Product for Seachem! Like their pH and Ammonia Alerts.....

Probably not much help, but: the Vacuum packers they sell at walmart, etc have a heat sealer for those types of plastic bags. If you know someone that has one........Maybe you could borrow it.
 

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Is that a shot glass? How did you make it? Once you understand how simple this device is, there must be a dozen ways to make one. The absolute simplest I have heard yet is to take a plastic tube, bend it into a "U" shape and cap one end. Of course a suction cup is still needed, but there are lots of options for that too.
what do you mean with a shot glass??

it's just a small cup..
 

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Discussion Starter · #154 ·

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Discussion Starter · #155 ·
what do you mean with a shot glass??

it's just a small cup..
The photo looked like the bottom of the cup was thick like a shot glass is made, so I just thought it would be a good joke! I keep being amazed at the variety of ways there are to make this little device. When I first thought seriously about it I assumed that the ADA type glass device was the only good idea - now we are down to a piece of tubing, a piece of breather bag and a rubber band!
 

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Sorry if this has been brought up already, but I didn't have time to read the 15 pages of this thread :)

If I didn't want to take the time to construct one of these, or buy one... and just wanted to do a quick test to see if my KH/pH chart method is fairly accurate, could I do the following?

1) Take a piece of tubing and seal it at one end and bend it in a U shape.
2) Use syringe/pipette to put distilled water into one end of the U and secure underwater in tank somehow.
3) Let sit overnight, take out next day during peak light hours when respiration is moving right along.
4) Test the pH and KH of this water and compare to the chart to get current CO2 level.

Would this work? I don't really need a day by day view of this and just want to see if the pH/KH chart method is accurate enough for my needs. I wouldn't need to buy anything, construct anything, or spend an hour getting distilled water to be exactly 4 KH.
 

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Discussion Starter · #158 ·
If you are going to use pH reagent to find the pH of the water you need to adjust the KH of the water to around 4 or 5 dKH, assuming you will be measuring around 30-40ppm of CO2. The color is just too hard to judge accurately unless you are reading about 6.6 pH. And, plain distilled water won't work because it has no measurable KH, so it gives an ambiguous reading of CO2. But, the device you describe will work fine.
 

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Discussion Starter · #159 ·
I'm not so sure the breather bag idea works. I've had a couple differnt models in my tank for over an hour and there is no color change.
Dennis, this idea has to work doesn't it? Assuming the breather bags really do allow CO2 and other gases to pass thru freely? The time it takes for them to reach equilibrium might be long, but I don't see how they can fail to work eventually. Tom Barr believes a device like this will have a short response time, but I haven't seen any data to say, one way or another. Of course a breather bag, used for its intended purpose, doesn't need to react very quickly. So, it is possible that the density of the pores in the bag material might be too small for the material to work rapidly for this.
 

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I think Tom is getting that notion from the fact that he plans to use DO probe membranes. The DO probe has a fast response time and works basically exactly like he has described in his posts. As usual though, I don't follow his notion of cheap since I can't find any that are less than ~$25 per membrane. I obviously don't know where he is looking as he never tells....

The breather bags should work in theory though don't know exactly how they work. There might be an issue with pressure across the gradient, or lack of with water on both sides. I really don't know much about osmosis type functions, other than the basics of things wanting to be at equilibrium.

I'll let them float around longer. It is possible that there is to large an air space above the indicator sample. Let me say what I did... I took a small specimen jar with a snap on lid, about 10ml volume. I cut away most of the lid leaving only the outer rim. Placed a small piece of Kordon bag over the opening and snapped on the lid rim. Works great. The hole in the lid is about 1/2" diameter. I added 1ml to this and placed it inverted in the aquarium so that the indicator solution is sitting on the Kordon. I also made another that has a 3/16 hole but the container is 7ml and I used 2ml of solution. This one is tall and skinny compared to the first with is shorter and wider. Neither is showing a color change after ~3hrs.
 
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