First Grow: Dr Lemon

Aim for the lowest figure on the guide and maybe even take a couple of mil per L off as well. I never go anywhere near the recommended strength. Hopefully you have a ph meter as that needs to be pretty exact although I find 2ml ph down per 10L gets my ph to around 5.8 ish. Keep a eye for tip burn on the leaf to let you know if you have used a little more feed than the plants want.

Algae is growing off the moisture and nutrients left in and on the perlite. It won't harm your grow. Best of luck the rest of the way.

Tent will always be 5-10 hotter then your atmosphere around it due to lights can try an make vents to pull cool clean air from room. for humidity control you can get a small humidifier you can pre set what you want it to be at. Just a lot of trail an error to correctly figure the perfect but I environment. I would definitely try to exhaust the air from the tent out the closet due it sucking out hot air an putting it back in. Another thing you can do is get some small 6in desk top clip on fans to put in the tent also to get more air circulation.

You could put a flange inside the tent facing out, tape the edges of the flange flat to the tent inside wall with duct tape and attach duct hose to the flange with hose clamp + tape. Or just skip the flange and tape the edges of the hose with duct tape but it might not be secure. If you forego the flange, you could push the hose in through the tent and run a small bbq skewer or stick the size of a bottle rocket stick across through the hose like a line going horizontally through a circle (the vent duct) then tape the stick/skewer and hose edges flat to the tent sealing all cracks. This would prevent the hose from falling loose easily without obstructing airflow. This application is literally what duct tape is for no matter what you do, seal it good for those odiferous runs. Best luck