I’d only be guessing. I think if you have larvae living in the hydro, nematodes should survive for a while. Nematodes don’t have feet like the target larvae, so they’d rely on the water flow to get them into place. They can be used in a pressure sprayer so I’m sure they could survive your hydro pump. They do just fine in coco.
Here is the place to go if you need specific information like using in a hydro:
I contacted them before my first purchase to see if I could use them with feed. The answer, BTW, was yes, just don’t mix them with the nutrient concentrate, because that would probably kill them.
They also carry other natural predator types for different types of infestations. Kind of a one stop shop for predatorial solutions to pest problems
I hope this has been some help. 