A little help please pics in the post

Hi guys I have made a post a few days ago but I haven't had a reply I have just removed 5 today my most of my plants are healthy as new growth is great but its worrying why in losing these leaves please check pictures and any advice would be awesome

Some information about your grow would be helpful. Medium, lights, nutes, pH, environment, feeding schedule, etc.etc.etc.

Are these lower leaves your removing?

Looks like nute burn to me guys, how much are you feeding and what? If it was n def or lack of light the lower leaves would turn all yellow first, they are not.

Apparently the OP is MIA.

If just a few leaves towards the bottom/center of the plant are doing this, you are probably totally fine. As leaves either become too old or get chocked out (mostly by lack of air flow, sometiimes to lack of light) they begin to "sacrifice" themselves, so to speak. They are simply transferring the mobile nutrients within the plant leaves to other places on the plant. Your 4th picture shows two beautiful, healthy plants. I don't think it's a deficiency or an imbalance.

Hey guys thanks for your replys so I'm still having this happen and have noticed that some leaves look fine from the top but when I hold up to light I can see brown spots within the leaf it seems to be getting worse I'm in soil under a 600w light pH is 6.5 .temp is 26 degrees celcius feeding budzilla which I've used last 3 grows never had a problem but I did notice when flushing last night I have thousands of white bugs in soil which only come up with the water I'm pretty sure they are springtails all I have noticed it starts with the spots on the leaf then brown tip leaf turns yellow and eventually half the leaf turns brown and crumbles hopefully after a good flush I can reset and hope like hell it doesn't carry on