I would use EMT. Electrical Metal Tubing is thinner than pipe and plenty strong to support a single Tao light.
Home Depot sells them in 10' lengths I think and you could probably bend it In their rental section.
3/4" EMT with a 90 bend at the top and a 45 kick at the top of the tank to get it to the middle. 1/2" would work too.
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