I was considering a small setup for highland nepenthes, and after getting quite a bit of information from this forum, was wondering if anyone could offer me some advice. I'm trying to provide a 5-10F night temperature drop, targetting 60-65F; perhaps some daytime cooling as well. Increased humidity is the secondary objective. Here's what I was considering:

1. Keep a jug of dist./RO water in a refrigerator (~40F, I think), either in my full size or in a cheap adjacent mini-fridge.
2. Run an ultrasonic fogger disc inside and into the jug of water.
3. Cap the jug except for a tube to direct the fog into the tank. Tube should be small enough for the fridge door's rubber seal to just close around it.
4. Set the fogger on a timer as needed.

This seems way too simple to be original, so apologies if I'm stealing someone's idea. Anyway, ostensibly this would provide 40F mist to the tank at any time; however, I have no experience with ultrasonic foggers, so before I invest in anything, please feel free to shoot holes in this plan. For instance, I have no idea if a fogger will have problems operating in cold water. Nor do I know if the disc will heat up the water too much (or if at all).

For additional info, here are my constraints:

I live in San Francisco, which has pretty good natural humidity (~50-80% RH outside, ~50-60% inside according to my therm/hygr). My apartment can get to 85-90F during the day, but outdoor temps drop to 45-55 at night, year round. Problem is, I like my apartment warm (70F min. at night). My understanding is that this is fine for intermediates - I have an N. alata spotted that appears to be doing well and pitchering after a month on my windowsill. However, I'd like some a highland or two, specifically hamata (surprise...).

My place is fairly small, so I can't do a dedicated cold room, or even a big terrarium. What I had in mind was providing just enough of an enclosure around the plant(s) to hold in the fog and provide a micro-climate so that they're happy and I'm not shivering at night. I should probably mention that I do have a fairly large deck where I grow all my Sarracenias, as well as an outdoor grow rack covered with shade cloth. I know that some people have grown highlands successfully outdoors here year-round, and I'm planning on trying it with maybe a maxima, but a hamata..? I'm thinking it'll love the night drop, but it'll dry out too much in the daytime.

What do you think, should I try them with the fogger, or just throw them outside, or just give up and settle for a ventricosa? (not a big fan...)

Thanks very much for any help/suggestions; I certainly appreciate it.