Having a problem with brown spots on the leaves. I...

Hi @Danno! This looks like pH fluctuations, and the beginning of a nutrients lockout. Get a pH pen asap and make sure your solution is always buffered within the 6.2~6.5 pH range. Now about the overwatering, be warned this often leads to nutrients-lockout issues. Roots need to be on a wet/dry cycle to properly develop and spread, searching for water. Do you let the soil dry a bit between each waterings? Let your medium dry and flush it with plain pH'd water at 6.2pH with the lowest EC. Then let it dry again, help it with a small fan blowing onto the container's surface, and once it's almost dry give it a good meal following the schedule of your choice with the fertilizer of your choice. I can recommend BioBizz, GreenLeafNutrients, GreenBuzzLiquids, these have worked great for me with FastBuds strains. Hope this will help, let us know how this goes, happy growing! 👊

The problem you have here is your grow light is to close back off to 24 inches at least till veg is over then slowly lower the light in flower inch a day. Put your hand right over plant and keep there for 30 sec if this is uncomfortable for your hand then it will be for the plant. All that cuping of the leaves and yellowing on top are signs grow light is to close.

I presume you're not giving any nutrients yet as they're not listed. And I presume you are checking the pH as that is important that in soil it should be around 6 to 6.5. This is important as many nutrients cannot be absorbed out of this range. Cannabis likes a wet/dry cycle like most plants really... Which means you only water when the soil has been left to dry for a few days. That can mean only watering every 2-6 days sometimes until it gets bigger and likes to driiiinnnnk. Hope I've helped. If you think you're over watering then you probably are. But must check your pH level!