I am currently comparing two different air purifier units, both outside side by side.
1. One has the GMC-300 on the intake filter of my newest air purifier model.
http://www.walmart.com/ip/Holmes-AER1-Mini-Tower-Air-Purifier/221764432. The other is my old air purifier model with the GMC-200 on the face of the intake filter:
http://www.amazon.com/Holmes-HAP242-UC-HEPA-Desktop-Purifier/dp/B0000DK35B/ref=sr_1_2?ie=UTF8&qid=1387398140&sr=8-2&keywords=holmes+air+purifierChart members can compare the graphs of each, links below. When you compare the graphs, please make sure you only compare for example the last 48 hours of one with a 48 hour graph of the other for the best view. I am testing these both to see which one I like best overall. So far, the GMC-200 on the older style air purifier seems to show more of a defined rise and fall in the trends. It is fair to say that with the newer model purifier & the GMC-300 unit, even though the trends are not as defined as the other unit, they are still seen. Please do not compare the CPM, this is not so important to compare as the time you see a rise vs. fall between graphs. Different geiger counters can easily vary on their counts like different scales.
This is where NETC works so well to find what the normal CPM range is with each different geiger counter/station and set RADCON levels based on that level. Each different type (regular tube vs. pancake) of geiger counter can have RADCON alerts at the same time even when their CPM are very different.
I suspect that the reason the detections seem to be higher/defined on the older unit might be because the GMC-200 is a smaller unit which does not take up as much room on the filter. This allows the purifier more filter to trap more particles and therefore increase the levels of radiation. I am happy to see that both units seem to show a rise & fall around the same times. The newer unit with the GMC-300 is a cleaner/easier install of the geiger counter. When using the Raspberry Pi with this new purifier unit it also seems to make a more portable unit. I hope to later (after testing) make the time to create a video showing how easy it is to use the GMC-300 with this new air purifier. Of course the GMC-200 would work on the newer model air purifier too, but using the GMC-300 it is nice to have the display of the current CPM visible through the cover of the air purifier. The GMC-200 has no screen! Plus using the GMC-300 vs. the GMC-200 you don't need as many wires which makes for a cleaner install.
All your comments, positive or negative are welcome. Thanks in advance!
Holmes HAP242-UC HEPA Type Desktop Air Purifier with GMC-200
http://netc.com/chart/view.php?n=1%3AEB5A139CHere is the Holmes AER1 Mini Tower Air Purifier with GMC-300
https://www.netc.com/chart/view2.php?n=1:EBD4A7EB