Nute Burn Week 6 Flowering - Is just water the answer??

My Magic Bud plants are just starting Week 6 of Flowering and are looking great from a bud perspective. However, after my last res change (doing straight DWC in 10 gallon tote) I put in the usual GH series nutes (2.5/5/7.5 - Grow/Micro/Bloom per gallon) and added 40ml of Sweet for the first time. My PPM read ~700 which is very conservative but these plants are EXTREMELY senstive to nutes. Now, I am seeing alot of bright yellow spots on the leaves which is definitely nute burn.

My question is, would it be best to do another res change and only put in water for the rest of the grow? I was planning to do a flush starting next weekend, since they are supposed to finish in 8 weeks and that would give me 2 weeks with just water. Would 3 weeks with water be a bad thing?

Not including any pics since I know what the issue is - just wanted to know if 3 weeks at the end with just water is OK. Thanks for your help. By the way, this is my first grow - so I don't have any experience to draw from.

3 weeks with plain water is way too long...

hell even 2 weeks is...

i dont even flush for 1 week.. just a couple days.. here is why...

the last few weeks of the plants life it swells the most.. it is trying to get the flowers as big as possible to catch pollen.. since it means their survival if they do.. this means they burn the most nutes the last few weeks.. taking nutes away during these times can drastically affect the end result of your buds.. you may lose a potential of 25% or more in size stripping the nutes away...

in my opinion you only need to flush for a couple days.. some people say longer.. some say not at all... i personally think 2 or 3 days is plenty enough... if you can use a flushing agent, like florakleen, all the better... not only will it flush your plants, but it will also flush out your system which is nice..

but in regards to your problem... if you are this far into flowering it could just be that the plants are starting to suck everything from their fan leaves in preparation for harvest time.. which is absolutely normal.. some plants, by the time you go to harvest them, have no leaves on them at all... so dont assume its burn.. posting pics would be a good thing... it could just be a normal thing!

also, you know what your ppms are, but what about the ph?? if your ph is off you could have other issues like lockout...

2- 3 days flush is plenty if you use a long cure when drying.

theres some crap called "super thrive" its way mega hyped, and doesnt meet its press.
but it does do wonders for fert burn.

id do a res change to pure water, (with a few drops superthrive), let that go for a few days to clean it out, and start it back at 1/4 nutes or less, do a slow increase.

Thanks Simpson - that was very helpful. What you said makes perfect sense even though I know there is alot of debate on the issue of flushing. I have also thought the leaves might just be getting to the end of their life. The only reason I think I burned them was that many bright yellow spots appeared within 2 days of my adding Sweet to my usual GH nute mixture. My pH has been right in the good range - between 5.6 and 6.2 consistently and res temps are always around 70. Believe me - I struggled with these factors at the beginning of my grow and learned alot from my noob mistakes. I will definitely get some FloraKleen. +rep

NOW - thanks man, great advice. I can't afford the SuperThrive at the moment but will let them have just water for a couple of days.

NOWitall said:

2- 3 days flush is plenty if you use a long cure when drying.

theres some crap called "super thrive" its way mega hyped, and doesnt meet its press.
but it does do wonders for fert burn.

id do a res change to pure water, (with a few drops superthrive), let that go for a few days to clean it out, and start it back at 1/4 nutes or less, do a slow increase.

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I respectfully disagree with the Super Thrive application. From what the Master Gardeners say, not me, (I don't have a fu... clue), this ST acts like an IV in emergency situation for... drought stress, lack of nutrition, but NOT for over ferting. That is gasoline on a fire. Call your local Master Gardener at your local Nursery, or maybe the library at the dirt doctors. It's potent, be carefull with it. Hope this helps.

South Texas said:

I respectfully disagree with the Super Thrive application. From what the Master Gardeners say, not me, (I don't have a fu... clue), this ST acts like an IV in emergency situation for... drought stress, lack of nutrition, but NOT for over ferting. That is gasoline on a fire. Call your local Master Gardener at your local Nursery, or maybe the library at the dirt doctors. It's potent, be carefull with it. Hope this helps.

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South Texas - Thanks for the info on ST. Can't afford it anyway so I should be OK.