plant turning black after i upped the CO2

[Marquis de Sod]

i have this plant that had the leaves start dieing off and turning black and it is right in front of the fan, which has my hose from the co2 tank on it. (is about two months into bloom). there are plants to the left and right of it as well as all around the room that are (or were) normal. so i took it out and killed it off, and put another of the same plant there (both indicas). in two days, the second plants leaves started turning black, as in dieing. (about 6 or 7 weeks into bloom). Is this the co2 or what? i don't get it. both plants next to this position are unchanged and the whole room is normal except these two douche-nozzels. my co2 level read 1550 at the highest. and has to build up to this point over night where it starts around 550. it is not on a ppm activated switch i just leave it on at a certain level that gets to a max of 1550 after 12 hrs.

any thoughts appreciated. thanks.

still killing them softly

 

[Dkgrower]

Idk - but check with u hand how cold it get when the CO2 is released or els u might be right but i have newer had such a problem so i am just guessing =)

 

[Marquis de Sod]

yeah, i'm fuckin stumped man. all my other plants look awesome. these two were on opposite sides of the room as well. temp was about 90. both were indicas, but most of the others that look great are indicas too. man these things really have dropped dead, too. got to start thinking what i might have put in the water the last few waterings. nothing out of the ordinary.

 

[Dkgrower]

Strange, i have big fans and when night temps get low, the fans can make em black in 2-3 days- if on full power and blowing direct on the plants, this only goes for indicas.

Strange they are in the opposite side, makes me think it has to do with circulation of the air - are the leaf tips drying out and become crisp ?

 

[Marquis de Sod]

i THINK i figured it out: i had been leaving my co2 on constantly low and after a few hours it would be about 1300 ppm. i started giving it more when i first turn on lights and then lower it, so it got to `1300 ppm sooner.

i think the high volume of the co2 blowing on the plant, which was where the oscillating fan stopped for a couple seconds before it changed directions, made it COLD. the gas is cold as seen by the gauge freezing up when too much comes out. so i think i have been freezing my plants off, cause only the plants that were right there in that same spot died off. i just killed my third one now, same spot.