We have learned some new information about the salmon in the classroom filter media that will hopefully help us to lose fewer fish this year. There are three kinds of media in the filters: mechanical (the white pads) which filter the particles of waste out of the water; chemical (the charcoal bags) which neutralize harmful chemicals; and biological (the black foam pads & to some extent the carbon pellets) which form a surface to grow on for the beneficial bacteria that break down the ammonia and harmful nitrogen compounds which can kill the fish. The mechanical filters need to be rinsed frequently and replaced periodically; the biological filter elements are considered a permanent part of the chiller, improving each year in their nitrogen handling capacity. They can be rinsed at the end of the season, but need to be reused each year. Discoloration just indicates that they are doing their job. Last year, because the filters were new, the number of beneficial bacteria was minimal, but should be better this year. To beef up the filtering ability of the filters this year, please add the new media we bring to the existing media from last year, and don’t substitute it for last year’s media.
For those of you with rod chillers, your biological media varies with the brand of filter you have, but, in general, are your sponges, plastic grids, and bio wheels. These should be replaced only if your old ones are broken.
To further help the beneficial bacteria have a chance to build up before the eggs arrive, you could leave your filters running over the break, but after testing, turn the chiller off until you return in January.
It will be required for you to release you salmon this year into the body of water indicated on the WDFW permit which we will bring each of you. You will then report the date of your release and the number of fish released to us as usual. You do not need to report the number of hours spent this year.
Yakima Basin Environmental Education Program 