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While searching the internet for Nitrate removal in aquariums, I stumbled upon this small article on a U-Tube de-nitrification column. Please read it. I've listed a few questions about it after the article.

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Home Made De-Nitrification Column

If the filter cannot be partitioned or you use an internal power filter, you can construct and use a denitrifying column. This consists of a "U" shaped piece of plastic plumbing pipe. The tops are left open and are made 3in higher than the water level. The column is placed next to the aquarium. A piece of airline is placed into one end of the column and an elbow attachment is fitted at the other end, just above the top of the tank level. The column is then filled with a porous filter media, so as to provide as large a surface area as possible. The airline is then fitted/ adapted to fit the outlet of the filter. The filter then forces water down the airline tubing, which in turn passes through the column and returns to the aquarium via the elbow placed over the side of the tank. The water flow is slow and once anaerobic bacteria are established, then denitrification occurs. It should be noted that anaerobic bacteria may not establish as quickly as its aerobic counterpart.

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Has anyone used or heard of theis method for de-nitrification?
My questions are:

1. The"u-tube" pipe, what diameter? Will 1/2" work?
2. The porous filter media it mentions, what kind?
3. It says an airline is fitted to the outlet of the filter. Would tapping into the suction tube of an HOB filter with 1/4" tube work?
4. The info I've read on de-nitrification coils talks about a system that is low in oxygen for it to work right. How is this "u-tube" idea low in Oxygen?

Your thoughts on this article is appreciated.