Plant Problem. +rep for opinions

Hi, I'm what you might call an advanced newbie. I'm on my first grow & I already found the right combination of Mycorrhiza to get bigger & better developed roots.

About 3 weeks ago, I started loosing a lot of leaves. Many of the leaves had some yellow in them so I assumed it was a N deficiency. Also, a lot of the damaged leaves looked a little different from each other so I may have had more deficiencies than just the one. (or more than just one problem)

So about 2 weeks ago I fed them with a full dose of FF Tiger Bloom and a full 1/4 cup of blood meal in the 10 gal containers. Then about 3 days later I watered with just plain water. I was still seeing yellow in the leaves so I then fed them about 3 days later with a full dose of Alaska Fish Emulsion & a full dose of FF Tiger Bloom.

I'm still loosing a lot of leaves, but I don't see much yellow anymore. A couple of leaves had some yellow, but only a couple out of over 100 leaves that I just lost off of one plant.

Also, about half the leaves I lost just fell off. Either when I was dragging the plant through the apartment, when I was reaching for a different leaf, or when I grabbed the leaf to Fan it (it just came off in my hand with little to no pressure). This part is brand new, very few leaves just fell off before today.

I'm pretty sure it's not because of an N deficiency. I thought maybe the petroleum oil (Bonide's All Seasons Oil Spray that I've been using to get rid of Broad Mites) might have been drying out the leaves since the leaves start drying out at the tip & edges of the leaves, and since some of the leaves had one half (left or right) that was dry while the other half wasn't. But I stopped using that spray about a week ago and I had to pull some leaves that didn't exist the last time I sprayed (they're brand new leaves). So now I have no idea what it might be.

So my question is if this looks like any deficiency that anyone's ever seen, or if anyone ever had a deficiency that caused the leaves to fall off iwth little to no pressure?

Another possible culprit I though of might be the lights. I have two 400w HIDs on most of the time on a 24/0 schedule. If the plant doesn't get enough light, will it kill off leaves to adjust?

+rep for any & all help.

P.S. I should also explain that when a leaf starts to dry out it first gets darker & softer, almost like it's water logged. The tips then start to curl and then the tips start to dry out followed by the rest of the leaves.

I have my lights 12" above the tops of the plants so I don't think it's light burns. And I try to keep it between 72 & 80 degrees. The portable A/C turned off a couple of times this past week and the temp got up to close to 100, but only for short periods of time. So I don't think it's the heat.

looks to me like like a bit of nutrient burn. id flush em with plain water no feed then after a few days try nutes at half strength n work ya way up.

also check ya ph.

Yeah-that looks like you want to lay off the nutes for a bit. Also Ive talked with FF a rep. and he stated to me that the chart they give out gives a lot of people problems. He told me to use half of all the liquid nutes. Go by the less is more rule. Me and others on here have also found that if you add the solubles too the mix you will start to lose leaves and have problems. Thats even using them at half strength! Funny,I was thinking the same about myself after I went out and got a jar of Great White w my last order. Then I read a good thread about it in the advanced teq. section, turns out it doesnt seem to do all that good for mj. Life cycle is to short to get any real benefits. Check it out,GOOD LUCK!