leaky frontier pro filter?

Just a guess, but it could be because they're making the threaded sections shorter and cheaper on the water bottles.

I have used my FP filter with a Platy soft bottle. I simply screw the filter straight onto the top of the Platy and then filter the water through. Even when screwed together tight, if I do not hold a little pressure against the filter and the Platy there will be a few drops that will run down the outside of the filter from the Platy. So, I must take care when filtering water in this manner so that it does not contaminate my "clean" water. Of course though I do chemically treat my water before filtering it through the filter…

This can be seen in my video here:

http://sticksblog.com/2011/06/29/a-closer-look-at-the-aqua-mira-frontier-pro-water-filter/

I dont have any experience with the frontier pro.

I have a sawyer squeeze.

It mates to platypus connection (basically 2L bottle).

AND it has a foam washer to seal against the top of the platy lip.

Have you tried a washer inserted into the female screw on part?

If you cant find one, you can make one easily. Hobby lobby has foam EVA sheets in 1/16, 1/8, 3/16" thicknesses.

Yeah, the "green" bottles have shorter fittings with smaller caps.

Have you tried it on a 2L bottle by any chance? I know mine wont really fit one L bottles , but fits 2L fine. But its made to work with platys and the saywer equivalent, not standard .5L and 1L bottles.

Have you tried a different brand of water bottle?