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For those who don't read many other aquatic plant forums, Tom Barr did some experimenting with this device and came up with the idea that you could get rid of the air gap entirely, and speed up the response rate considerably, just by using a gas permeable membrane to hold the reference KH solution. Then, if that membrane is in the form of a stocking over the business end of a pH probe, you have a CO2 probe - with fast reaction and great accuracy. He has done a prototype, of sorts, and it works. And, he is working towards getting this available for all of us.
I would imagine, for testing purposes, that the "Breather Bags" that people use to ship fish in would work for a membrane--The Bag--let's C02 Out--Oxygen In. Reversed (into/toward the Drop checker): its should let the C02 In. But will it let it back Out to maintain equilibrium? Hmmmmmmmm.....

Needing one clarification: Drop Checker fluid--set to Kh 5 will read the same C02 ppm as what is in the Tank? Meaning regardless of tank Kh (2, 6, 8, 12 whatever) the ppm of C02 in the tank will match the Kh4 Soultion? I can almost grasp that, but it just doesn't seem right.......:rolleyes: I looked at the "Table" posted:

Table Link

And I'm just missing something. I'll re-read that a couple dozen more times and see if I can get it to "Click"........:rofl:

Thanx!
 

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Ok, Thanx. I understand what You are saying and I actually was typing out a response when I think it clicked. So, let me see if I have this right:

X-amount of C02 will create X-ppm regardless of Kh.

The Higher the Kh--the more C02 it will take to create X-amount of change in pH.

BUT, since we are not concerned with the pH in the Tank--it becomes irrelevent. The focus is on the pH change in the Drop-Checker because 30ppm is 30ppm--regardless of Kh, Correct?

If we matched the Kh to that of the Tank--then we would just be chasing the "Color Scale" and making it more difficult, Correct?

I think I've got it--just need confirmation.....
 

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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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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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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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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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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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