A nose heavy condition can cause excessive speed on landing but since you say the plane tends to float on landing it is probably not that. Flaperons can cause tip stalls on landing. What I have done is used spoilerons. With spoilerons the ailerons reflex up and a little down elevator is mixed in to keep the plane level. By reflexing the ailerons up you are inducing wash out which helps avoid a tip stall. Spoilerons decrease lift and increase drag making it easier to land a fast plane. Check to see if you have a spoileron function (air brake function is the same thing) on your transmitter. Also you will need to have your aileron servos on separate channels.

Bruce