Basic

Here is a couple of pictures of my DIY drop checker. It is made of 1/2" hot water pvc pipe. I am using phenol red in it. It gets a yellowish - orange at about 6.2. I also use the blue in my other drop checkers. I like the contrast of the two colors. It won't win a beauty contest. The glass vial is from a tropic Marin test kit. All the pieces can be bought at a hardware store. I also use 3 silicone O rings to hold it on tight and keep air in and water out. I don't remember where I saw the original. It takes a little bit longer than the other drop checkers to register your co2. But you save about $ 10 to $ 40. Good luck!

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pjb9166

Basic

I hope you don't mind me offering another design. Since you started a thread it would
be redundant to create a thread with the same content. My wife bought me one of those dish washing scrub
sponges you fill with soap. I removed the sponge and cut off the side you fill the soap.
I then used a heat gun and a spring pipe bender to shape it. Total cost $1.00.
I failed with a design that consisted of
a tiny bottle and a piece of tube. There was not enough surface area for gas exchange.
The solution never changed from blue to green. The Co2 was on all night so I decided
to turn up the Co2 to this weared number of 4 bubbles a secon. I wound up gassing all
my fish. Well in my tank I only have one bubble per 2 second and my new drop checker
tells me my Co2 is fine. My new checker is cool I think and works great. Not bad for a Newby.

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pjb9166

Basic if you don't mind me asking. After filling the drop checker when do you have to change the solution. Is the reaction suppose to go both ways. If Co2 drops will solution turn back to blue?

Basic

I change mine about every 2 weeks. You may be able to go longer but I just don't chance it. Yes as the co2 drops it will change from yellow (at its highest) to green (about 7.2) to blue, which is about 7.5 to almost 8. I keep mine in yellowish -Green area because of the difficult plants that I have.

mangisda

might try that.