the thing to remember is that the plants need pk at the end of flowering. it's actually the N that you want to reduce in the last week while letting the pk increase. so when you reduce the A+B, you get exactly the effect you want, ie lower N, while the pk still is maintained by the coco it's self. i spoke to a very respected grower at the 420 who put it very succinctly. basically he said you want to reduce the N by 25% each week in the last 2 to 3 weeks before flush. while increasing or maintaining the pk levels. he was not talking about coco specifically, but the point remains. you are doing pretty much the perfect thing at the moment, lol. if you really wanted to you could go out and get one of those finishing products to use in the beginning of flush, but it's not needed, i always use water and it does a great job.