I have been reading some about ammonia, nitrites, algae etc. and it
appears that no effort is made to maximize the removal of ammonia
using filters for fish pond owners. I have been doing some research
on the removal of nitrates for individual (home) wastewater treatment
systems for environmentally sensitive areas and believe the
intermmitent sand filter would be of use for fish ponds. There are
many sites on this topic and here is a sample of what is available:

http://www.wisc.edu/sswmp/pub_15_24.pdf
http://www.septic-info.com/doc/display/59.html
http://www.extension.umn.edu/distrib...es/DD7670.html

In 1999 research produced information on the best operational methods
for the conversion of ammonia to nitrate and then nitrate to nitrogen
using the intermittent sand filter, a very stable and reliable
treatment method.