Beginner needs help w Yellow leaves & interesting pattern

Your growing outdoors?

Ok sorry just saw the 300's, bad eyes lol. The pots too big. That will cause root rot as the roots aren't getting back to a dry oxygenated state fast enough. 3 gallons is plenty for all autos since they are tiny even at full vertical growth. You need a faster wet to dry cycle, So I would transplant asap. Also are you using distilled h20? 5.5 will lockout phosphorus, calcium & magnesium in soil.With that expect death. You should be aiming to get the runoff to 6.2 max low and not lower. Weed loves acidic but not that low and 6.5 is perfection. 7.0 bottled water is what I use and a lil acidifier. Now keep in mind going over 6.6 starts to lockout other nutes such as iron and manganese. Minor compared to what your dealing with. Good luck my friend but be decisive and correct the problems diligently.