04-30-2019, 05:59 PM
It may be that the 5 micron carbon block filter is pretty much all 5 micron holes whereas even a 1 micron yarn wrapped filter still has a few 10 or 20 micron holes in it.
That was my thought as well. When I was shopping for filters last time I noticed that the fine print says something like (for a 10 micron filter) "blocks 95% of particles over 10 microns and 99% over 20 microns". Which isn't very good!
The results from the 1 micron polypropylene filters were especially interesting. The 1 micron didn't let any through and the 5 micron only a very few, but the last run tested them after letting the filter sit for a while, flushing through water that didn't have any worms in it. So that showed that worms that had stuck on the filter before, were able to get through when it was restarted. I wish they had done more replicates though, because one of the 1 micron filters let none through, while another let in 64, much more than any of the 5 micron filters. I wonder how the different brands vary as well. I expect they're pretty variable, but it would also be a huge amount of work to test them.
The pump can't draw from the top of the tank, because it has to be able to pull water when the level drops. But I believe you can get a float so that you can pull water from just below the surface (you don't want to get stuff that's floating either). Pulling from just above the bottom is probably good enough anyway.
Lisa Kaluna, one of the authors, said on FB that they're in the process of testing UV systems now. The worms apparently aren't killed by UV sterilizers (tough buggahs!), but it's not clear whether they are still infective.
That was my thought as well. When I was shopping for filters last time I noticed that the fine print says something like (for a 10 micron filter) "blocks 95% of particles over 10 microns and 99% over 20 microns". Which isn't very good!
The results from the 1 micron polypropylene filters were especially interesting. The 1 micron didn't let any through and the 5 micron only a very few, but the last run tested them after letting the filter sit for a while, flushing through water that didn't have any worms in it. So that showed that worms that had stuck on the filter before, were able to get through when it was restarted. I wish they had done more replicates though, because one of the 1 micron filters let none through, while another let in 64, much more than any of the 5 micron filters. I wonder how the different brands vary as well. I expect they're pretty variable, but it would also be a huge amount of work to test them.
The pump can't draw from the top of the tank, because it has to be able to pull water when the level drops. But I believe you can get a float so that you can pull water from just below the surface (you don't want to get stuff that's floating either). Pulling from just above the bottom is probably good enough anyway.
Lisa Kaluna, one of the authors, said on FB that they're in the process of testing UV systems now. The worms apparently aren't killed by UV sterilizers (tough buggahs!), but it's not clear whether they are still infective.