Aaron Langley
You should invest in a proper flash, the higher power and shorter duration will allow you to get more motion frozen and probably increase your hit rate.
Satoshi T
I've thought your splash series is under the flash light. but now I read @Aaron 's comment, I recognize you use continuous light 1/640th Exposure. I recomend to try off-camera strobe.
Aaron Langley You should invest in a proper flash, the higher power and shorter duration will allow you to get more motion frozen and probably increase your hit rate.