Not true, Liquid.
In a 2.5 there is no cycle anyway - less than 5 gallons doesn't really hold a cycle. In over 5 gallons, which has cycled, even a 100% water change won't remove the cycle. Very little of the beneficial bacteria is contained in the water.
What will kill a cycle is replacing or over-scrubbing your filter, which is where 90% of the good bacteria is.