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I finishing up my DIY HOB skimmer. It's a counter current air driven skimmer. The length of the reaction column is 18" long and 3" diameter.

What type (size & manufacturer) of powerhead would be recommeded to introduce the water into the top of the reaction column and provide enough power to push the water back into the display tank. The water inlet (not shown on sketch) is located about 2" from the top of the reaction column. The skimmer will be used on my current 15g high tank then moved to a new 40 gallon tank. Also what brand of air pump would be recommended to supply adequate air to the limewood airstone?

Thanks.