Different strains of dino have different ways of eradicating. The most common and easiest strain is the one that will be eradicated with raising pH level and magnesium.
I once had a dino attack that no matter what I did, it came twice as hard. I eventually found out that the more water changes I made the more it was feeding on the new nutrients from the wc and thus helped to fuel it.
So I stopped all wc and waited it out, and one day the dino went away as fast as it came.
Just to ask, do you notice and increase growth after doing wc?