My N.rafflesiana (and to a lesser extent my N.coccinea) have unhealthy-looking red spots on their leaves. They are being grown about 6" away from a pair of 32w daylight T8's next to a bunch of highland Nepenthes with leaves that have healthy-looking tans. The lights are on 16 hours a day.
Both lowlanders are growing very slowly, and the N.rafflesiana is developing pitchers, but I'm wondering if the red spots are indicative of something that might be preventing these plants from growing at a reasonable rate.
Too much light maybe? Let me know if you have any ideas.