How (and why) to Make Reusable Tank Caps

Photo of a diver sticking masking tape to the side of their tank to demonstrate why reusable tank caps are important in preventing marine debris.
It’s not unusual for divers to rip masking tape off and stick it to the tank or the side of the boat. When this happens, the tape can blow into the sea and become another piece of marine debris.

As a diver, there’s nothing more disheartening than the sight of plastic or other man-made debris taking over our favourite sites. Yet, despite many efforts to move away from single-use plastics or reduce hazardous chemicals from entering the sea – such switching to reef-safe sunscreens or making eco-friendly cleaning products – many dive operators don’t realise how much debris can still enter the ocean as a result of using masking tape, instead of reusable caps, for your tank separation system. As environmental champions, it’s our responsibility to ensure our activities don’t hurt the health of coral reefs and marine ecosystems. Making reusable tank caps is one thing you and your staff can do to keep our oceans free of pollution. 

Read on to find out the problem with using masking tape to signal a full tank and how you can make your own eco-friendly alternatives.

Why make reusable tank caps?

Using masking tape to indicate a full tank is fairly common practice in dive schools around the world. It’s not unusual for divers to stick the discarded tape to the tank or side of the boat. But have you thought about what happens to this tape once it’s been torn from the tank neck? 

The problem with using adhesive tape is that the stickiness wears off easily, resulting in the tape blowing into the sea and becoming just another piece of marine debris. Even if you ask guests to dispose of any making tape in the bins (whether they kit up at the dive shop or on the boat), there’s always the chance they might forget or inadvertently drop their tape. A few little pieces of tape may not seem like a big deal but, with millions of divers getting in the water each year, the impacts soon add up.

The good news is there is a cheap and simple solution at your fingertips: reusable tank caps. You can, of course, buy tank caps but a cheaper and more environmentally friendly option is to upcycle old materials – like compressor tubes – and make your own.

How to make reusable tank caps

To make your own reusable tank caps, you’ll need: some old compressor tubes, a saw, a stanley knife and some thin but strong rope. Ready? Here’s what you need to do:

1. Measure the size of the tank cap

Using the tank valve as a guide, measure where the old compressor tube needs to be cut to create the correct sized caps.

2. Cut the tube 

Using the saw, cut the tube at the point that was measured.

3. Cut two notches in the tube

With a stanley knife, cut two notches in the compressor tube. Make sure they are at opposite ends of the tube but on the same side as each other.

4. Measure an appropriate length of good quality rope

Measure out an appropriate length of thin but strong rope using your forearm.

5. Tie rope around the tube, securing it in the notches

Using a slip knot, tie the rope around the piece of tube and secure it to the notches.

6. Tie the cap to the neck of the tank valve

Finally, attach the cap to the neck of the tank valve using the slip knot.

Now you have a functional and reusable tank cap! To watch our step-by-step guide to making your own reusable tank caps, take a look at our video.

If you have any questions or you’d like to share information about a great environmentally-friendly solution you’ve found for your dive operator, please feel free to contact