Thrips in DWC

Hi! Not new to growing but new to indoor DWC and loving almost everything about it except THRIPS. I'm on my 3rd round of them, each in different grows. I have NEVER seen an adult thrip flying around or even anywhere on the topside of a plant. I find them each time when changing out a reservoir, usually one with a low fluid level to a new, full one. I usually check back the day after a nute change to verify PH and find the thrip larvae swimming around. I'm assuming they had colonized the damp, but not submerged roots and then get rinsed off when they get submerged in the new, fuller bucket. Once I find them, they are easy enough to deal with; I've done the H202, Neem Oil and Hot water root dip thing, all have been successful and I don't think I've ever had any thrips make it to adulthood before being wiped out, but my question is this... first, where are they likely coming from and second, how to I deal with this proactively? So far I've been lucky and caught it early enough that I've suffered very little plant damage but don't want to ignore the things either. EDIT TO ADD: After doing a little more research I could possibly be looking at newly hatched Springtails and this would certainly explain them being in the roots, they do also "jump" on top of the water. Anyhow, same questions though.