Had the same issue with my Vivosun inline fan after 1 month of use. Most likely the internal bearings rusted. Just installed the replacement ac infinity. Definitely more quiet but doesn't seem to push the same amount of air despite being rated about the same as the Vivosun.
If you haven't done so already you should reach out to Vivosun support. They were very quick to respond to my email and refunded my money after verifying a few details. Seems like a common issue.
@Fubar_420, in perfect run yes, under leds i had longer development, if i pushed them max - 10-11 weeks, if i need it now, i still kept them for 9-10 , only scoop and tricoms will tell.
For me maybe even 2 weeks of fed left by pictures, harvest them in parts , one or two keep boosting, others start to flush and compare the weights after. Every strain and every run is unique.
@Fubar_420, As long as it does not exceed 28º(In the highest part), you can have the lighting as close as you can. 😉
Sweet smokes and good luck!
-Apolo