Brown, Rust-like Spots on 1 of 5 plants

I realize there's plenty of this in other threads, but wanted to start a fresh discussion.

So here's my situation. First off, this is my first grow. Got 5 plants, Chernobyl strain. They've been outside thus far and approaching 9th week total since emerging from medium.

I water by feel, but typically over other day to every 4th day. Medium is Fox Farm Ocean Forest. Unfortunately, don't have any way to test soil or water PH. I've mostly watered with bottled spring water from local Co. (but occasionally tap water with a 24 hr+ aeration period to let the unwanted evaporate off),and their water analysis seams to average 7.22 pH. I know that's a bit high for cannabis plants, but I haven't had any noticeable issues up til this point.

Also, I just started adding nutes exactly 9 days ago. I'm using Fox Farm Grow Big. I started out with just a 1/2 teaspoon per 1 gl. But, the last two waterings were every 3rd day and I added nutes as I haven't noticed any burn or negative effects. The 1st of 2 I used the same nute to water ratio (1/2 teaspoon to 1 gl water). The 2nd, or last watering yesterday, I went with a 1 teaspoon to 1/2 water.

Am I too heavy on nutes to early? Should I have watered down with an extra 1/2 gl of straight h2o to water down the solution? Is this a nutrient deficiency direct or indirect? Is it simply a water pH issue?

Any input is greatly appreciated! I'm not super worried @ this point, but I don't want it to continue unabated. Pictures below. Thanks!

that my friend looks like phosphorus deficiency to me..

After my research and a little deductive reasoning, I think I've come to the same conclusion. I flushed with a bit of water earlier, so I imagine that if it is phosphorus deficiency then I won't notice a change or it will continue, even after a few flushes. Should I be concerned in the long run and try to address it, or should I give it time and see if there's change after flushing?

I would also assume that since the plants are pretty new to the nutes, I probably shouldn't attempt to balance the phosphorous by just increasing the nutes? Seems a little soon for that. Is some blood and/or bone meal in order? What are some other ways (preferably natural & organic) to raise the phosphorous levels? Should I be concerned with the magnesium levels? I wouldn't think this would be an issue with the the levels in the water I've been using, but who knows.

Here is a chart that shows deficiencies http://www.marijuanapassion.com/forum/showthread.php?t=54233

Thanks LILBSDAD, that's definitely helpful to have on hand. What would you say I'm dealing with from my pictures above? I'm honestly thinking either Nitrogen, Phosphorous, or perhaps Manganese. It's hard to be proactive when I don't have a definite. I guess I'll take a look tomorrow and see how things are looking. Probably be able to make a better decision then. Either way I think flushing pretty heavy wouldn't do any harm and I'll get some quick feedback. And suggestions?

i think your on the right track, flush first and go from their

For reference incase I do need to address phosphorous deficiency, what are some ways to do so? I mentioned blood and bone meal. I have some but it's the small pellet style that you would mix into the medium rather than spread on top. Doesn't seem like this would help that much as I imagine it would be slow time release. Any other recommendations?

Im thinking i may be having this same problem..im not sure whats the cause tho..is it an over fert, or deficiency?
View attachment 1716769

burn from over nutes or deficiency. that's the million dollar question, right? HD, give us some more info on your watering, soil, environment conditions, and nutes. Are there any differences or similarities in our grows? Although your pic looks similar to mine, your leaf looks a bit more yellow than mine (is this just lights and/or camera flash?) so I'm inclined to say that perhaps your looking at N deficiency or pH issue? Other than the picture you posted, are there any other characteristics you've noticed? Brittle leaves, anything with the stems, new and/or old growth, wilting, irregular growth, etc.? Take a look at the links below to get some clarity on ur situation and let us know. Same or not, let's nip this in the butt! Cheers!

http://www.weedfarmer.com/cannabis/nutrientdisorders_guide.php
http://www.weedfarmer.com/cannabis/tables_guide.php
http://www.420magazine.com/forums/problems-pests-disease-control/81275-cannabis-plant-pest-problem-solver-pictorial.html
http://www.marijuanapassion.com/forum/showthread.php?t=54233

oh and I'll take a look when I get home later today and see if there's any change. Probably take some more photos and post to help diagnose. Thanks for all your help and input guys!