Red petioles and curling leaves on my XJ13 plant that is 4 weeks into flower.

My XJ13 plant has been looking pretty healthy so far, but I have noticed that the leaves are beginning to curl and the petioles are turning red at the top of the plant. The plant is run in Fox Farms Ocean Forest Blend Soil and is getting AN Big Bud liquid every watering (beyond that it only received Voodoo Juice prior). I added no perlite to the mix but the aeration seems fine. The pH of the soil is running 7 so I feel it should be ok. Maybe I should try lowering it a bit? Any other suggestions?

Red petioles are red most likely due to a genetic trait, however if the petioles are red and the leaf veins are also it's a phosphorus deficiency. But there would also be chlorosis and necrotic spots with other symptoms. In "soil" we don't play with the p.h. especially run off as that won't tell you much other than you over fed or some other shit that you already know because you did it and it's no mysterious matter. Soil is buffered and p.h adjusted so unless the p.h is swinging wildly out of your faucet your good.

What about the curling leaf ends? I figured I could give it a bit more phosphorus so I fed her some Bloom Builder by B.cuzz Products that has a good amount of phosphate.

be careful, don't overfeed what looks like a pretty healthy plant because of some minor problems. ph your nutes to 6.5, check your ppm/ec, makes sure its not hot, then leave it alone for a while. i know the temptation to "make it better"...resist it.

Your curling leaf ends may be because you have overfed trying to correct a problem. Again, no need to p.h anything other than your plain water from the tap to see where it's baseline is.That's it that's all. Be careful of the Nitrogen it will curl your leaves if you use too much.