The 250ml Nalgene unit is a nice size, but will clog quite rapidly if filtering lots of dirty water. You also need to empty and replace the bottom container more often, of just use a 1l (or 2l) scott/duran bottle as a replacement for the supplied 250ml bottle.
DNA Preservation method used:
For short preservation times, filters can be directly placed in ATL buffer (Qiagen DNeasy kit). This works well if you are able to process the samples within 48h or you have a freezer available within that time.
For preservation longer than a few days, I tested Longmire’s solution. Works well, but only compatible with Phenol/Chlorophorm extraction, which is laborious and also does not yield the best and purest DNA.
Now I switched to using Zymo DNA/RNA shield. Have no test results back, but expect good results, and major advantage is that it directly fits into both the Zymo Quick-DNA miniprep Plus kits as well as the Qiagen DNeasy kit. And DNA will be stable at RT for 1 month.