Matt……“You mention epoxy, does that work and what epoxy did you use?”
>>>>>GORILLA. The Glue Guide by Gorilla does state, “Bonds most plastics, but not polyethylene or polypropylene as you had mentioned.” I have had no issues to date with the caps and as long as the adhesive holds the screen in place without fall out (my purpose) the cap pressure will do the rest.
Brenda…..“are the metal screens you guys are using fine enough to prefilter slit/turbid water for use with a steripen."
>>>>>I use my prefilters with my SteriPen when needed and that has not been that often as I am VERY SELECTIVE when it comes to the amount of dissolved and suspended solids in the water source I take my water from due to my suppressed immune system. When I use my Larson Designed Gravity System (Sea To Summit 8 liter Ultra-Sil Dry Sack, 5 micron (nominal) pre filter sewn into the bag, Sawyer .02 purifier) with my grandchildren I have also no issues and produce water in large amounts (Average 290 sec/liter) quickly when I suspend 1.5 gal at a time.
Prior to using a pre filter with the Larson Designed Gravity System, I had one big issue in it early testing with Lake Michigan Water in early Spring around South Manitou Island using water that had large amounts of suspended Cladophora algae that you could observe (a native algae species that washes up on the beaches when wind-driven waves rip it off the bottom of the lake and becoming a big issue for the ecology of the lake.) in the water. With my updating of the system I have had great success with many different water sources and “suspended solids” contained within.
Jerry…… “Even pump or gravity filters aren't that great for silt - they'll plug up for one thing”
>>>>> I had a silt issue at Lake Desor (North) on Isle Royale back when I was using a Katadyn Pocket filter (HEAVY, 0.2 micron ceramic filter (cleanable) without pre filtering the water on year, but I quickly corrected this by scrubbing the ceramic filter. (The suspended solids were so fine you could not discern with the naked eye. This island also had Cyanobacteria (Blue green algae) issues in the late summer and closes several inland lakes to the potential health risk to people who are exposed to certain species that contain a toxin. In this case if you see “blooms” or “scum’s on the water you are drawing from…..be conservative and do not use the water. People with other filtering device that used these waters were not so lucky, as thier filters clogged and could not be cleaned.)
Katharina…. “A 4" x4" piece of cheese cloth, folded twice, to make four layers. Works much better
(faster) than a bandanna and seems to catch a certain amount of silt too.”
>>>>This information may interest you:
Back in the lab I tested “grubby bayou” (Late Summer water in front of my house that is a good sampling source for these test.) water through various pre filter materials to determine what material makes the best pre filter. This is what I found out:
1. paper coffee filter - water very clear (as tap), filter rate very slow
2. cloth coffee filter - water tinge of yellow, filter rate slow
3. pelon material - water slight tinge of yellow, filter rate very fast
4. handkerchief - water tinge of yellow, filter rate slow
5. heavily used MSR towel (PackTowl® Ultralite) - water clear, filter rate fast
6. lightly used MSR towel (PackTowl® Ultralite) - water clear, filter rate medium
7. MSR towel (Nano™ Towel) - water clear, filter rate medium fast
CONCLUSION: The use of either the MSR towel (PackTowl® Ultralite or MSR towel (Nano™ Towel) would be the best pre filter material prior to UV, filtering, or purifying water with suspended solids (e.g. algae, bugs and floating debris.) Each of MSR pre filter materials can be washed in the field and used again and had has sufficient surface area to handle most filtering/purifying pre filtering needs. The use of a strong rubber band would aid in affixing the pre filtering material in place around a pot or liter btl/canteen so to enlarge the filter area.
NOTE: The QUALITATIVE nature of the water clarity is based on sight comparison to tap water or water that has been place through a paper coffee filter.