jennybugs
Eternally pruned fingers!
Ooh that crab is colourful. I'd put it in a tank of it's own too - ie an sump or such
Best thing to get the stuff off the rocks is a Turkey Baster, I only recently got one and I now believe they are an essential piece of kit. It is amazing how much detritus gets blown off that you cannot see until you use the baster. Once blown off you can then do a water change using a siphon. What you are blowing is likely to be any die off and this will help the rock to breathe and therefore increase its filtration potential.
It is likely to reduce the nitrates aswell although this is not necessary at this stage of cycling. Once the cycle progresses the bacteria will also reduce the nitrates as will the diatoms that form towards the end of cycling indicating it almost ready for CUC.
For Aiptasia, you can use Aiptasia X, Joes Juice (Both have mixed results, some can come back after treatment) or Seffies weapon of choice, the soldering iron, or my personal favourite (although I have not yet needed to) is the blow torch.
I am a mad scientist anyway so the tests I do on the tank just confirm this.