Question
Jacob,

i guess i had responded too many times. anyway, here are the answers to
your questions:
1. I bought three flytraps from you. two out of three are without leaves at the
moment.
2. i use water form a carbon filter system.

Answer
Thank you for the info, Marc!  Now I have a clear picture of what's going on.  Your flytraps are actually declining not because of the cooler temperatures but because of the water.  Carbon filters are excellent in removing chlorine, mercury, lead and organic matter, it doesn't remove calcium, magnesium or iron.  I know that the water in LA is a bit hard, and these minerals will burn the roots on your carnivorous plants.  (Carbon filters are fine to use only if your water is already low in minerals.)

What I recommend is repotting your plants in a fresh soil mix of 1 part sphagnum peat moss and 1 part perlite.  Repotting is necessary to remove the mineral buildup.  You can find these ingredients at your local garden center.  Make sure that there isn't any added fertilizer since some manufacturers will add it.  If you can't find any fertilizer-free ingredients, you can purchase the soil mix from our website.

When you repot your plants, check the flytraps.  If the base (bulb) is brown and soft, they may have already bit the dust.  If the base is white and firm, you might be able to salvage them.

Next use only bottled distilled water.  This type of water is free of all minerals, including calcium and magnesium.  Water filtered through a reverse-osmosis unit is also fine to use, as is rainwater.  Avoid using bottled spring water because the mineral content can be very high.  

Continue providing 6 or more hours of direct sunlight, or as much as possible at this time of the year.  Winters in LA are very mild, so you can keep them outdoors.  

Good growing!
Jacob Farin