Got a problem with my Snow White

Title says it all, Been having this problem for about 3 weeks or so, I know my pH isn't the best but I use my pH down to 5.5 ( With Nutes ) and within an hour it goes back to 7. My old growth starts with little yellow/brown spots like necrosis, later on they begin getting brittle and curling up, to me and anyone else it sounds like a MG def but I used Epsom salt ( 1 tsp per gal ) a week ago with no nutes ( I did foiliar feed though ) but it's just getting worse. Here is a thread I saw and decided to fill out to better explain whats going on or what could cause it.

How long has this problem been going on?
Are you growing in a PVC grow tent? (example: Hydrohut or any other non brand tents)
What system are you running? (DWC? Ebb flow? Aero? Water Farm? Flood Tables? and so on...)
What STRAIN are you growing?
What was the establishing technique? (Were the seed or clone?)
What is the age of your plants?
How long have they been in there mixture they are in now?(coco,soiless etc..)
How tall are the plants?
What PHASE are the plants in? (seedling, vegetative or flower) are the plants in?
What Technique are you using?
What substrate/medium are you using?(Hydroton, RockWool etc.)
What is the Water temperature?
What color are your roots? White? Brown? Are your roots slimy?
What Nutrient's are you using?(If growing soiless)
How much of each nutrient are you using with how much water? *Knowing the brand is very helpful*
How often are you feeding? (If using soiless)
How often are you giving nutrients? (If using soiless)
If flowering, when did you switch over to using Bloom nutrients?
What order are you mixing your nutrients? (example: veg nutes 1st, bloom 2nd ect)
What is the TDS/EC/PPM you are using
What is the pH of the "Tank"?
How often are you testing your pH/PPM/EC/TDS?
Are you sure your calibration is correct on your equipment?
When was your last watering?
What is your water temps?
When was your last feeding change? (ie. grow-bloom-micro-additional)
How often do you clean your system: example: Flush out water replace with clean water and nutrients?
What size bulb are you using?
How old is the bulbs you are using?
What is the distance to the canopy?
What is your RH Factor(Relative Humidity)?
What is the canopy temperature?
What is the Day/Night Temp? (Include flucutaion range)
What is the current Air Flow? (cfm etc.)
Tell us about your ventilation, intake exhaust and when its running and not running ?
Is the fan blowing directly at plants?
Is your water HARD or SOFT?
What water are you using? Reverse Osmosis (RO)? Tap? Bottled? Well water? Distilled? Mineral Water?
If using tap water, what is the ppm/EC/TDS of the water right out of the tap?
If using RO,Distilled,mineral water, what is the ppm/EC/TDS without any additives?
Are you using water from a water softener?
Has plant been recently pruned, cloned off of or pinched
Have any pest chemicals been used? If so, What and When?
Are plant's infected with pest's

And Here is a picture of the lovelys... ( E-Sarcasm works wonders >.> )
http://tinypic.com/r/fm5na8/7

Some of em are wilting
http://tinypic.com/r/f2v7le/7

And Some are curling upwards
http://tinypic.com/r/2ppy0yt/7

As I said earlier, I've flushed multiple times with 1/4 str nutrients to fix a possible nitrogen def someone else told me it might be, someone else told me it could be a mg def and I should put epsom salt in, none of these fixed it. They are also growing slow as hell, every other grow Ive had my plants were a foot tall atleastsby a months time and alot bushier.

I'm starting to wonder if these plants are savable and how the yeild would be, don't know if its even worth running my setup due to it, so any help would be very appreciated =)
 
Dont know how this got unfilled but here it is.

How long has this problem been going on? 1 month
Are you growing in a PVC grow tent? (example: Hydrohut or any other non brand tents) No
What system are you running? (DWC? Ebb flow? Aero? Water Farm? Flood Tables? and so on...) Dwc
What STRAIN are you growing? Snow White
What was the establishing technique? (Were the seed or clone?) seed
What is the age of your plants? month 1/2
How long have they been in there mixture they are in now?(coco,soiless etc..) month 1/2
How tall are the plants? 6''
What PHASE are the plants in? (seedling, vegetative or flower) are the plants in? Veg
What Technique are you using? Topping
What substrate/medium are you using?(Hydroton, RockWool etc.)Hydroton
What is the Water temperature?65
What color are your roots? White? Brown? Are your roots slimy? White
What Nutrient's are you using?(If growing soiless) Pure Blend Pro
How much of each nutrient are you using with how much water? *Knowing the brand is very helpful* Nutes are a 3-2-4 mix and I use 1/2 strength
How often are you feeding? (If using soiless) every 2 weeks
How often are you giving nutrients? (If using soiless) every 2 weeks
If flowering, when did you switch over to using Bloom nutrients?
What order are you mixing your nutrients? (example: veg nutes 1st, bloom 2nd ect)
What is the TDS/EC/PPM you are using tds
What is the pH of the "Tank"? 7, I use my pH down to get it to 5.5 with nutes but within an hour its back at 7
How often are you testing your pH/PPM/EC/TDS? twice a day
Are you sure your calibration is correct on your equipment? yes
When was your last watering? 2 days ago
What is your water temps? 65
When was your last feeding change? (ie. grow-bloom-micro-additional) 2 days ago
How often do you clean your system: example: Flush out water replace with clean water and nutrients?every 2 weeks
What size bulb are you using? 600 watt hps
How old is the bulbs you are using? Less then 4 months
What is the distance to the canopy? 1 foot
What is your RH Factor(Relative Humidity)? 50
What is the canopy temperature? 80
What is the Day/Night Temp? (Include flucutaion range) 75 day 65 night
What is the current Air Flow? (cfm etc.)
Tell us about your ventilation, intake exhaust and when its running and not running ? Portable ac
Is the fan blowing directly at plants? Yes
Is your water HARD or SOFT? Hard
What water are you using? Reverse Osmosis (RO)? Tap? Bottled? Well water? Distilled? Mineral Water? started off with distilled til the problem occured then went to well water
If using tap water, what is the ppm/EC/TDS of the water right out of the tap?
If using RO,Distilled,mineral water, what is the ppm/EC/TDS without any additives? 200
Are you using water from a water softener? No
Has plant been recently pruned, cloned off of or pinched Yes, topped and cloned
Have any pest chemicals been used? If so, What and When? No
Are plant's infected with pest's No
 
Top