So everything was going great till I decided to put an air register in my grow room. For about 3 days it dropped the temp around 22 degrees F between day and night. One of the plants , under the register, started getting almost an iridescent blue/purple color on the leaves and they began to curl down. The 2nd plant under it began showing black/brown looking spots center leaf. Growth has slowed to crawl on both plants day 26 flower. All other plants growing well enough. I shut the vent and now temps at night are within 10-15 F of day temps growth is still slow and spots keep popping up. Although slowed a little. Phosphorus?? Potassium?? Also anything I can do about it besides lose sleep?