He he he! You can get some cheap ones on ebay, be sure to get one with a high CFM than your fan can handle not lower.
I hear about busts regularly these days & its usually due to fires, snitches or scent.
Keep safe AgentP.
A CO2 filter is a must in the grow room/area, look at everyone's grow op 90% of them have CO2 filters not because they dont like the scent of MJ because they dont want to go to prison.
When I was started to grow I found out early on that no 2 plants will mature at the exact same rate even if they are kept within the same conditions.
AP dont worry your plants will be just fine though its only natural to over think & mother them too much I certainly did.
This should help explain:
https://www.rollitup.org/harvesting-curing/28072-harvest-time-tutorial.html
https://www.rollitup.org/harvesting-curing/188207-another-she-done-yet-first.html
From all of my 10 seeds the very last one sprouted & I kept it as a mother plant. My previous grows were crap but Im currently doing a perpetual grow the first 5 plants are in there 8th week of flowering though Ill give it a max of 10 weeks & Ill let you know how it goes.
I too am using Biobizz soils & nutes (Allmix, Grow, Bloom & Molasses when my skills improve), currently growing Blueberry.
Could you post pics of your op so we can see your ventilation & light setup?