DWC Help fast please.

I'm growing Master Kush in DWC and they are in their 2nd week of flower. For the past few days I've been running into issues with spots on all of my fan leaves (new and old). The situation went like this:

About a week ago the new growth started to look a little too yellow and my stems were turning more purple than usual. I decided on the next water change to add more bloom nutrients. I've been using GH Flora series (with added MagiCal)

On Saturday, I checked the PH when I changed my buckets and the PH was down to about 4.5 (I know that's really low, but the plants for some reason weren't minding it aside from some reddish stems).

I gave them more nutrients than usual thinking I've been underfeeding them. The PH was at about 5.2 and I repeatedly added enough General Hydroponics PH UP until it reached 5.8.

For the past few days since that change the plants have developed slightly necrotic lesions on the lower growth (Mg deficiency) and necrotic dots on all of the fan leaves on the plant. I need help identifying what these are. There are NO bugs, it isn't a pest problem.

My thoughts are as follows:

1. I changed the PH from 4.8 to 5.8 and so created some sort of shock to the roots.

2. I somehow locked up nutrients using too much PH UP.

3. The plant has been growing so fast (it's DWC and 2nd week of flowering) that I haven't been giving them enough micronutrients.

4. It is an Iron deficiency (I have been using MagiCal which contains some iron in addition to micronutrients)

Any ideas would be appreciated greatly.

keep your ph stable. and keep rez. temps 65....... dont overfeed and you will be fine

I'm pretty certain it isn't an overfeed, if it were I should have some sort of nutrient burn and I don't. Water temperature only really effects bacteria growth and Dissolved Oxygen levels not nutrients(unless they are REALLY low temps). I need to know if this is some sort of deficiency or if i threw the chemicals out of wack with PH UP or if I may have somehow shocked the plant into not taking up nutrients.

Purple stems in Master Kush is perfectly normal, as for the PH check it 2 times a day until it remains stable and once a day after, also the spots look like it could just be from misting your plants with the light on and burning the droplets of water with the magnifying glass effect.

It's easy to say keep the PH stable, but the PH has been stable at 5.8 for the past 3 days and the issue is getting worse... so either I shocked it bad or there is something that needs fixing.

I also haven't foliar fed at all this grow... It looks a lot like Ozone burn but I don't have an ozone generator.

this is a ph issue. dont have too muh of a swing on your ph..... check it daily....

What happens when the PH goes out of wack too quickly? So far I haven't had much of a problem changing it by .5 at a time... this time was a bit more of a swing than usual (but I also gave a lot more nutrients than usual and had to use a lot more PH UP than usual)

"Osmotic Shock Damage to the roots" is apparently what happens... now the question is how quickly will the damn things recover if that is the problem.