Old scuba tanks, be it steel or aluminum, are prone to corrosion on the inside when left unused for a long time. If you spot a little too many of those questionable rust spots on the inside walls of your tank, there’s a high chance your tank will get caught in the radar of visual inspection.
That’s when you know that your tank needs a good old tumbling to restore its interior health. You have two options: one, pay your local dive shop owner to get your tank tumbled (usually costs $50-$80), or better you can do it yourself. This guide will cover all aspects of the second option. Here’s one for self-sufficient scuba divers!
So, without further ado let’s get into the nitty gritty basics of tumbling your scuba tanks at home.
Table of Contents
What Is Scuba Tank Tumbling?
To put it simply tumbling is the process of smoothening rough surfaces, often metallic (usually caused by rust) to make them uniform and shiny. The metallic object in our case, is the interior walls of a scuba tank.
Scuba tanks can entrap moisture on the inside when left unused for too long or improperly handled during filling. Needless to say, moisture is the main culprit behind the corrosion of metal. The more severe your corrosion is, the harder it becomes for your scuba tank to pass visual inspections let alone hydrostatic testing.
Tumbling involves filling your tank with a diluting solution, a tumbling media (usually coarse crystalline chips, more on that later), and then placing your tank horizontally on a pair of spinning rubber rollers called the rotary tumbler. The rolling motion that your tank goes through causes the tumbling media to scrub out the rust spots from your tank walls to make them smooth and shiny again.
Now that we have a rough idea of what tumbling is, let’s move on to the actual step-by-step guide of Tumbling your tank at home.
The Ultimate Guide to Scuba Tank Tumbling at Home
Tumbling your tanks at home can become a real cost-cutting strategy in the long run. Tumbling does require an initial investment of around $500 to buy a rotary tumbler (or you can make one yourself for 1/5th the price, here’s a YouTube guide on making a tank tumbler from scratch).
Time Required: 30-45 minutes
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Prepare the Tank for Tumbling
Start by removing any rubber valves or other accessories from the tank.
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Pour the Tumbling Media Inside
Next, pour a small styrofoam cup worth of aluminum oxide crystals into the bottom of the tank. These crystals will act as a scrubbing agent to clean the interior.
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Add Water and Soap
Place your tank horizontally and pour water inside the tank till it’s about half full horizontally. The water helps carry the tumbling media to all nooks and crannies of your tank.
Then add 1-2 drops of dishwashing liquid. I prefer to use Dawn Soap. The soap will help break the surface tension of the water, allowing the aluminum oxide to clean more effectively. -
Seal the Tank
To prevent water from spilling out during tumbling, you need to seal the tank. Insert an O-ring seal into the tank’s neck. Shake the tank to make sure no water is leaking out.
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Place Your tank in the Tumbler
Place the sealed tank horizontally on top of the rubber rollers. Turn on the tumbler and set the timer according to the level of corrosion you want to remove (usually 10-30 minutes is enough). The tumbler will rotate the tank, allowing the aluminum oxide to clean the interior thoroughly.
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Rinse the Tank
After tumbling, remove the tank from the tumbler and carefully pour out the aluminum oxide crystals and water. Rinse the tank with fresh water multiple times to remove any remaining crystals and soap.
You can also give your tank a final rinse with hot water to help with the drying-out process better. -
Visually Inspect Your Tank
Take a quick peek after rinsing your tank to ensure there are no rust spots left. If you find a little too many left after the first round of tumbling, it’s time for another. Repeat the previous steps once again.
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Blow Dry Your Tank Thoroughly
Drying out your tank is probably the most important part of this process. Connect an LP hose inside your tank to completely blow dry the last drop of moisture from your tank’s interior using dry compressed air from another tank. If you have a compressed air station at home, even better.
I’ve heard some people say they use vacuum pumps to suck out the moisture but I cannot vouch for its effectiveness.
And that’s it! You’re done transforming your rusty tank into one as good as new. Now let’s tackle some common questions you have in mind regarding tumbling scuba tanks.
How Often Should Scuba Tanks Be Tumbled?
The process of tumbling gradually thins out the metal of your tank interior. So don’t tumble your tank every time you see a small fleck of rust inside.
So that begs the question: how frequently do scuba tanks need to be tumbled?
That entirely depends on how you take care of your tanks when not in use.
If you’ve taken all measures to prevent your tank interiors from catching rust (getting your tanks inspected regularly, always keeping your tank half filled with working air pressure when not in use, blow drying the insides of your tank once a month, and so on) your tanks can go as long as 2 years without significant corrosion and in turn, the need for tumbling.
But Getting Tanks Tumbled at Dive Shops Is Easier
Absolutely! Getting your tanks tumbled at dive shops is more convenient than tumbling them at home by yourself. But the purpose of this article is not convenience, but self-sufficiency, and maybe saving a bit of money along the way.
I have already created another guide for filling scuba tanks at home and plan to create more such guides in the future.
The scuba community is known for its creativity and feats of self-sufficiency. You can always bring your scuba tanks to a dive shop for tumbling and be done with it. Or, you can brace the challenges of learning the process yourself and be self-dependent. The choice is yours. If my guide helped you take another step towards becoming a self-sufficient scuba diver the pleasure is mine.