ph problems, and plants dying in dwc systems

[one2threeBUDS4]

so i started with 2 different 12 bucket systems under 6 lights using botanicare tri-flex (first time using)... i usually use gh flora nova... my ph seemed to go up very rapidly and kept landing around 7.2-7.3... i then tested the tap water and the ph came out 8.0, at this point i figured the drops were wrong and maybe went bad??? so i bought new drops and a new ph meter too.. (my plants are dying during these 2 weeks of hell).. after buying a new meter and comparing those results to the ph test drops the ph is around 7.0-7.2 but i cant get it to go down, ive flushed the 100gal system around 10 times and had to pull all my clones and start over.. i rewashed ALL of the hydroton and cleaned the shit out of the systems and now i am so confused as to why this problem is happening again with the new batch. the clones seem to be yellowing on the young leaves first and eventually killing the plant... THE PH WILL NOT STAY BELOW 6.5 AND SEEMS TO RISE VERY RAPIDLY. im now tripping balls and the 4 people i know that run over 10k watts cant figure it out either... it takes around 30ml of ph down to get my ph in my 30gal res to drop to the right ph but after the res drains into the system and 12 hours passes, the ph is back up between 6.7-7.2..

help me please if u know what youre talking about, if you seriously dont know or are just trying to throw wild guesses at me = thanx but no thanx.

 

[Enjoy!]

okay well the fact is i dont know if this is the problem though, when you make your water/nute solution and make your ph as you want it will be that, though even 1 hour from than it can be tottally different depending on how fast it can evaporate into the air( meaning if you have an open resivior in your grow room the heat will make it evaporate faster) and when it evaporate only the water does, not the nutes. so in this case you have more nutes than you want( bad for plants) and can switch your ph in crazy directions.

 

[one2threeBUDS4]

okay well the fact is i dont know if this is the problem though, when you make your water/nute solution and make your ph as you want it will be that, though even 1 hour from than it can be tottally different depending on how fast it can evaporate into the air( meaning if you have an open resivior in your grow room the heat will make it evaporate faster) and when it evaporate only the water does, not the nutes. so in this case you have more nutes than you want( bad for plants) and can switch your ph in crazy directions.

thanx for the response enjoy! seems very logical but my resevoir isnt open but still could be a problem