DWC pH fluctuations 6.5 - 4.5 in 24 hours

[OzbudboY]

Everyday I check the pH it shows about 4.3 and I adjusted up to about 6.5 and within 24 hours its back down to where it was in the 4's..
Parts per million is slowing going up every time so I keep adding just plain water to try and lower the parts per million because I don't want nute burn. I had nute burn weeks ago in veg and that's the old burnt you can see on the tips. I've been having a lot of leaves dying off at the bottom that dont see much light. I've been seeing the deficiencies for about a week now but its hard to correct when the ppm keeps going up and im lowering the ppms and trying to adjust the ph at the same time(i end up adding lots of base). Now I I can't tell if it's nute burnt again or it's some sort of a deficiency this next photo is what I believe to be a potassium deficiency possibly potassium and magnesium. Picture was taken a few days ago, mostly lower leaves are having the problem.

The plant is in 4th week of bloom and it was in vegetative for about 16 weeks

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These last 2 were taken today, looks like the tips are yellowing.

 

[Serpent]

Hey there how are you yes i remember last weeks you have some problems what size is your DWC if its a few gallons its hard to keep everything in check and it will bounce around if the temps are not right as well

 

[OzbudboY]

It's 5 gallon, I have the nutes so low I don't understand why it's burning. I haven't changed the water since they went to bloom

 

[Hillbilly420]

Make sure your water level is fine, but over 20ml of down or up, the plant starts to burn like that. Man I had the same thing going on in my last dwc. I changed my water and lowered the water level where it would be a inch or so below the net pot. Then everything started to even back out where a person had to ph water every 3 days. Man I hope this helped ya.
Oh yea make sure you ain't got any rot going on. I heard it makes this problem also.

 

[OzbudboY]

Make sure your water level is fine, but over 20ml of down or up, the plant starts to burn like that. Man I had the same thing going on in my last dwc. I changed my water and lowered the water level where it would be a inch or so below the net pot. Then everything started to even back out where a person had to ph water every 3 days. Man I hope this helped ya.
Oh yea make sure you ain't got any rot going on. I heard it makes this problem also.

Thanks, I'll consider getting what you suggested. I've been topping up so the bottom of the pot is covered up to an inch. Thanks for the tip on why it's burning. That would make sense, I do add a lot of base everyday..... I guess I'm at a point where I'm going to completely change the water and had no idea what ppm to shoot for.

 

[OzbudboY]

This plant drinks close to a gallon and a half every day

 

[OzbudboY]

could be rot, doesn't look too slimy though

 

[OzbudboY]

It seems to be getting worse. I did add some h2o2 which help keep the pH high at 6.8.the next day i changed the water and changed to advanced nutrients. It doesn't seem to be affecting bud production but it looks like I'm losing a lot of leaves now, any more suggestions? Could this be caused from all the tie downs I still have on the plant?