COCO COIR Is this yellowing a sign of something bad?

[JayGee]

The rest of the plant looks fine, its the lower leaf that's been almost dragging on the coco. It also seems to be the least thirsty, as its had the greatest amount runoff ( though ive dialed its fertigation back a bit).
Temps 22-24 celcius. Humidity is 43-45% with the exhaust fan on low ( and humidifier on high). The other plants seem fine.

 

[Colombo]

watering_coco May this will help in your use of COCO, Look up, does COCO Coir have nutrients ( yes it does) Good Growing !!