Is this nute Burn?

Can someone please tell me if this is nute burn?

Apollo 13 5.5 weeks into flowering.

Fox Farm products used as per sced.

Also sweet raw

Water every 3 days as needed with nutes.

Temps between 68 and 74

Humidity at 40

Looks like light burn although some of the pics look like nute burn.. maybe both?

and you should only be feeding them once a week. the rest of the time .. straight water

The lights are atleast 2' from the tops.

The fox farm feeding sced. says to feed twice a week. I never had a problem feeding twice a week.
but I have never used promix or the sweet raw before this grow.
thanks for any imput.