Not sure how I ended up staring at videos underwater of the pantanal but one thing always baffled me and thats why it is so clear compared to any other bodies of water ive seen. This video isnt in english and I cant understand hardly any but I think he is talking and showing the sand bottom and how the water is filtered by it. Id love to know more and know if anyone has tried to replicate it with a reverse undergravel filter and deep sand bed. My guess is you would need a high head rated pump but why not turn the whole tank bottom to a sand filter?
BRASILIEN PANTANAL - Expedition 2011: http://youtu.be/i9cwsEs4tuY
BRASILIEN PANTANAL - Expedition 2011: http://youtu.be/i9cwsEs4tuY