Thrips

That does not look like thrip damage to me, I also don't see any thrips on the leaves. If I had to guess this is an issue with your feed and roots. If your in veg, then using things that are not designed for flower is fine as your in veg not flower. But again I don't think this is thrips and you should not use things if their is no reason to. You don't need to kill anything from the looks of it, You need to properly identity the issue and treat it, After checking your nutrients and tools "calibrate them" double check your lights and timers. Sometimes lights are to strong or on to long with no breaks or the plant grew to close to them. Good Luck!