Got some white patches on the leaves first grow so...

depends on recent behaviour and could even be nothing to worry about. if it expands, that's more than a blemish... if not a young plant, less likely just a blemish. so, if you have been feeding regularly, back off for a day or 3 and see what happens... react to worsening conditions, but be certain of it. if you've been light, try fertilizing a bit more frequently. more often issues related to nute symptoms are not caused by a toxicity or deficiency... simply look on our fertilizer as to what it provides... if there is a significant Ca component, it's not likely a Ca deficiency even if it presents itself as such. pH, ratios of elements and concentrations of elements are all a more likely cause in that case. generalization: So, be conservative with this... eliminate possibilities based on behaviour and products used recently or consistently. If 2 choices exist because the problem is unclear, i guarantee you will save yourself future problems if you take the path that doesn't invovle dumping random shit into your soil, coco or reservoir - et al... always easier to add more.. always quicker to fix a deficiency, if it is really one, so you can better react to those as you ease back... without compounding the problme as you are still figuring out what it exactly is. if anything you've done lately makes what i say bat-shit crazy, ignore it... so many possibilities...

Could just be some nute water you dripped on a leaf or two. Unless it's rampant. I wouldn't worry! Happy growing!