I am growing in homebase multipurpose compost which seems like it is high in nutrients. I water every 5-6 days with rain water and I have a fan blowing into the box. I'm using 2 30w 6400 cfls about 3-4 inches above the plant.
I am guessing this is nute burn.
Could anyone give me any advice about how to fix this or if I should wait it out or straight away change something?
Maybe a little more info would be helpful.
Is that soil you mentioned just straight compost?
If that is straight compost, it is way too nutrient rich.
Also compost is living, decomposing matter. It can also generate it's own heat during decomposition. I make compost in a bin outside, and when I stir it in the morning, you can see steam coming off it.
Sounds like nutrient lock out, but without pictures and watering schedule, nute schedule etc.. it is hard to speculate.
If it is straight compost, I would mix it with some other relatively neutral grow medium like Fox Farms Light Warrior or topsoil. (also perlite or vermiculite)
I make my own soil, and I also use compost,(and several other organic supplements) but never just that alone.