<span class="link_user">@FarmerBobNasty</span>, To be completely honest with you, 50% in week 3 is pretty low for optimal VPD. At typical tent temps (25–26°C), you're sitting at a VPD of around 1.4 kPa, which forces the stomata to partially close and slows down early growth. Ideally, you’d want 65–70% right now for explosive veg.
If you don't want to buy a humidifier to keep it low-cost, try turning down your exhaust fan to trap natural transpiration, or hang a damp towel in front of an intake fan. Once you hit mid/late flower, that 50% will be perfect, but right now a bit more humidity would really help them take off! :facepunch: