Yellowing chlorosis from humidifier?!

Just posting this up because I had a real eureka moment this week. My seedlings grow in the laundry room, which is normally fairly humid to begin with, so I don't have to humidify. As the temps dropped recently and the heat came on more often, I decided to use a supplemental humidifier.

My tap water is fairly chlorinated, so I always let it sit a long time before I use it for watering or nute mixtures. The pH is naturally right around 6.5, so that's not a concern.

About a week or so in with the humid, I began to notice a few of them begin to yellow on the larger leaves. I tried flushing, increasing nutes, decreasing nutes, everything, the problem worsened. A few days ago, I walked in there and noticed how much chlorine smell there was. A quick check of the symptoms of chlorosis confirmed my suspicions.

I was filling my humidifier tanks with straight tap water, and it's been messing with the leaves. Also was causing premature yellowing in the bloom room as well, since I have the same humid in there. The yellow leaves are a lost cause, but the new growth looks green and healthy.

Just passing this along, in case anyone else is having a yellowing leaf mystery. Grow on! :cool:

Good find brah!

If you can smell it that strongly, your water company is still using Chlorine gas.

Not sure if it's the only culprit here.
High humidity alone can cause those symptoms as the plant struggles to transpire.
Eliminate the chlorine and see if it continues.

Mahalo fo' da info.

Weezard

Hey homey Rumpl -

Are you saying that you think the over-chlorination is due to the humidifier because it hasn't had a chance to un-chlorinate if you're using straight tapwater without letting it sit? I wouldn't have thought that enough of the humidity in the air would enter the leaves via foliar feeding for the chlorine to affect them in that manner, but I guess the foliar feed is more substantial than I thought. I realized that feeding with non-dechlorinated tapwater can cause those symptoms, but never thought that the humidifier could do the same! I assume that the 2 small tubs of tapwater that I store in my cabinet could cause the same thing, but at a MUCH slower rate because they're not actively pumping in.

Yes, that seems to be the case. The humid chamber doesn't allow gassing, and when I opened the tanks, it did reek of chlorine.

I reached this conclusion reluctantly, because it doesn't seem that it would be easy for this to happen. But I'm out of ideas, since it's the same room I always use, same soil, same everything. I normally don't humidify, since this room is naturally a bit "wetter" anyway, but this time I decided to see how the grow would go with higher humidity.

Another issue is that they don't seem to be responding yet to the humidifier being off, but it's only been 4 days, so I suppose patience would be the best virtue. But I'll continue to post on this as things develop. The yellowing seems to have leveled off, but the growth now is almost nil. They haven't grown at all since almost 2 weeks ago.

I also did a few experiments - transplanting a few, trying a shot of Superthrive, etc. So far, no difference. The only positive news is that the centers are still very green and healthy looking, they just are not growing much at all. And these had come out of the ground like they were on a mission.

If your tap is hard and/or heavily chlorinated, it's going to mess up your humidifier eventually as well. It's a pain but I run only distilled water through my humidifier. I hate using tap for any aspect of growing because it's really not good for the plants. As many old-timers around here will tell you, tap water in general sucks. Also when you pH, if you're using paper make sure you let it sit in the water for at least 30 seconds. Because the tap is unbuffered it takes longer to get an accurate reading.

Okay, I need to fess up. I DO indeed have heavy chlorine here, but that was most likely NOT the cause of the seedling issues. I apparently had grabbed the wrong soil when I re-potted. I used composted cow manure with worm castings added, instead of the plain cow manure. The little buggers were OD'ing on Nitrogen, I believe.

Believe it or not, adding Eco Bloom (heavy in phosphorous) on top for 2 waterings brought them back around, although they seem to have lost a few weeks of growth. The sicker ones I carefully "root cleaned" and re-potted in FF Happy Frog. All but one survived.

Thanks for the posts, all.

Thanks. Yes, I do have to clean the filters a lot. I have a distiller, but it's an all-day job to fill a tank, plus the unit really jacks up the temps in the room it's in.

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Originally Posted by Chromophore

If your tap is hard and/or heavily chlorinated, it's going to mess up your humidifier eventually as well. It's a pain but I run only distilled water through my humidifier. I hate using tap for any aspect of growing because it's really not good for the plants. As many old-timers around here will tell you, tap water in general sucks. Also when you pH, if you're using paper make sure you let it sit in the water for at least 30 seconds. Because the tap is unbuffered it takes longer to get an accurate reading.

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Thanks. Yes, I do have to clean the filters a lot. I have a distiller, but it's an all-day job to fill a tank, plus the unit really jacks up the temps in the room it's in.