Okay... listen up kids! In todays science class I'll show you how to make a pH indicator for your fishy tank.
We will need the following:
- an empty small plastic bottle, like they give you in hotels to wash hair and stuff
- a small rubber band, like they use when you buy fish in the pet store
- a rubber suction cup from the spare bin
- a zip tie
- a breather bag
- something made out of white plastic, like an old credit card, Nutella cover, etc
To assemble, poke two holes into the suction cup and push the zip tie through it. Cut the plastic bottle with a sharp knife, maybe in half. Cut a piece of white plastic that goes on the bottom of the container, which makes it easier to see the coloration of our pH indicator solution. Cut a piece of breather bag to fit over the opening of the container.
Twist tie the suction cup to the container. Drop the white plastic piece into the container, and test the rubber band to make sure you didn't cut the breather bag too small. Add some 4 dkH water and indicator to indicate 30 ppm, or use 3 dkH for 22 ppm, 5 dkH for etc etc.
Works. In this case, the air space is a bit too large, so the drop checker tilts upwards. Either I need to cut the container shorter, or add more water.
After looking at it for a few weeks I get tired and throw the thing in my "interesting but useless gadgets" bin.