Having read numerous posts on this and other forums, I couldn't bring myself to spend upwards of $70 or more for a couple drop checkers for my tanks. So I decided to take a trip to my local surplus store, The Axe Man. I'm not sure if they are a nation-wide store, but there are a few around the Twin Cities here. They have just about anything you might need, at (usually) great prices. So, with some ideas in mind, I set out to see what I could find. And this is what I came up with:
The small glass bottle has a plastic cap with a hole in the center. Included was some sort of foam or plastic gasket/seal. The test tube is plastic (important as you will see).
What I did was to punch a hole in the gasket with a paper punch, just a tad bit smaller than the diameter of the test tube. Then I cut off the closed end of the test tube to allow air to flow through it. I suppose I could have used some plastic tubing from the local hardware store, but this was cheaper and available. Next, I push the test tube through the gasket, screw on the cover, grab a spare suction cup and attach with a rubber band, and viola! No waiting for glue to dry, and very easy to change the solution, since the cap is removable.
I tested filled with water for leaks, and found none. I am using DIY 4 KH solution (if anyone wants the details on how I made that, I can follow up with another post). Here is a picture of it in action:
It's a bit on the blue side in this shot, but I took this picture about 7 hours after the CO2 and lights went out.
My only concern with this setup is, it takes about 4 hours or more before I get a nice light green color. The indicator solution is VERY slow to change, but it does change. I suspect maybe my test tube doesn't have a large enough diameter to allow maximum air / gas exchange. I may play with this later on.
Anyhow, cost break down is this:
Glass bottle with cap = $0.35
Test tube = $0.15
Rubber band = free
Suction cup = free
Indicator solution = essentially free
Total cost = $0.50 and about 10 minutes of time.
Please comment. I'm open to suggestions for improvement.