Go to the hardware store and get one of those sprayer they use for ex terminating , pump action and they are usually a good size and cheap. Just don't put any pesticides
From what I've read and assume you have your plants looking nice Bro. I have a few questions and several comments.
How tall are they?
Are you still using 6500K bulbs and if I read right that is 4 total correct?
Did you ever get and use your T5 ?
Gnats:
When you get your pot ready for medium (Soil,Coco, Etc. ) put a layer of your medium, then 1 inch or so of sand,then fill with your medium and leave about 1 and a half inch or so from top. Add a inch of sand to top and you wont have any gnat issue .
Yes to HP or hid or whatever the 150 over CFL was. CFL is cool, cheap light and can grow weed no doubt but at that watt level I'd go with HP.
Hopefully by now and if not, you should be using 2700K bulbs for flowering/budding. You should see a great thickening of buds if you do. Put as many as you can and the 42 watt ones are not that expensive.
Happy growing bro and I look forward to your finishing grow and smoke report.