Fungus gnats are only interested in soil that is kept TOO moist so the odds are 10 to 1 that you are over-watering, keeping the soil too wet. Plants will "wilt" just as readily from too much watering as they will from too little since it causes root rot. So let the soil dry out and if the plants begin to wilt, wait. Give them at least 12 hours before watering and you'll likely find that they have perked up all on their own. From then on use the finger stick test to determine if they really need water of if you just "think" they do. ;) You don't indicate your zone or location in your posts - you really need to do that - so can't judge your weather demands but 90% of gardeners over-water their plants and fail to understand that plants can cope with too little water much better than they can with too much water. Dave

gee, perhaps I am being visited by aliens each spring....

What type of lamp and ballast (if any) does the thing have?

Not without investigating it. Hate to tell you I don't know of any AC contractors that are fortune tellers with crystal balls. I can't tell you how many times a year I get someone who calls me wanting me to diagnose a system over the phone. LOL. If you want a guess go buy a magic 8 ball. I'm not in the guessing game business. If you want a quiet unit I can install one that is so quiet you won't even hear it run until it engages Stage 2 and even then it's quieter than what you have now. But I know you don't want to hear that do you? Realize I said it would be me installing it. So if you don't live with in my service area you are left to your own resources. This is the truth, much of which no one wants these days. Run to the nearest gimmick provider for safety.