Humidity over moisture

Samjpikey

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Hey guys done a search but there's too much different information around to get a clear answer sometimes ,
Starting a tank With a dry start method primarily means 'dry start' not moisture start ??

So humidity is the key ?? Not moisture , so I'm guessing Maintaining humidity over 90% is a lot more important then misting on a daily basis ?

Cheers
 

Michael W

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I haven't tried to DSM before due to owning low tech tanks and not being comfortable with adding CO2 whilst flooding but I am currently starting to grow Ludwigia Repens and Staurogyne Repens emersed. I have kept the Ludwigia for a week with success and I don't mist everyday. I make sure the substrate is wet and the cling film tightly wrapped around the contain making sure theres condensation inside at all times and its currently growing nicely.

For some reason I find the Cat Litter substrate I'm using is keeping itself wet. The bucket of cat litter which I had left from rinsing has been left for 2 weeks without water yet its still wet so I think that plays a part in the emersed container.
 

Samjpikey

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Im now on the 12th day of my dsm and all seems well , seems like all plants are rooting well and seen a lot of new growth in the hair grass but noticed one staurogyne leaf has started to discolor .
I'm thinking I could be over spraying as humidity is high ,temp has been no lower then 22c.
I just need to clarify that humidity is key over the daily spray and consider spraying a lot less frequent .
I do how ever leave the lid off the tank for 25 mins every morning for air exchange then place a small container of boiling water to gain back humidity, maybe in doing that along with the daily mist is adding to much moisture.
I don't want my plants thinking that they are transferring to a submerged state and start to melt etc etc .
 

foxfish

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I believe both methods work with some folk swearing by their own personal experience, as you know I keep the lid shut & humidity high & use bright light to obtain fast growth however others do indeed spray, so obviously both methods work.
I have posted quite a few pictures before.. but here is a hybrid one...outside, with heat mate & slightly vented lid but no spraying...

490c3c4f3a476b00c9e0185c509446a6.jpg
 

m_attt

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mine was lid on tight, light on for a long time. tank was always steamed up misted plants every few days. Hc and styro carpeted in a few weeks
 

Samjpikey

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I haven't misted since yesterday morning and surprisingly all looks better :) .
Do you think I should prune the longest shoots of the staurogyne of just leave it to fill ??
 

dw1305

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Hi all,
If you have really high humidity you don't need to mist. There used to be a product called a "dew point propagator", which worked on 100% humidity, and it was very successful, partially because the plants never had any visible water on them. You just placed it some-where cool, and it then kept your cuttings at 100% humidity.

cheers Darrel
 

Samjpikey

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So Darrel ....

In your opinion Having no visible moisture on the leaves is not going to damage the plant and 'dry' it out ??

Cheers
 

m_attt

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my styro looked dry through my whole DSM, (apart from after misting) tanks was steamed up all time and It was and is healthy and green.

you can see in this pic


9014483503_7e2a462e22_c.jpg
 

Samjpikey

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Did you only open lid for air exchange whilst misting ?? Was it just a lite mist ?
Cheers
 

dw1305

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Hi all,
In your opinion Having no visible moisture on the leaves is not going to damage the plant and 'dry' it out ??
No, not if you have 100% RH. What causes the damage to the leaves of the plants, and stops cuttings rooting, is when moisture is lost more quickly from the leaves than it can be replaced by the transpiration stream through the xylem from the root to the leaves. What defines the rate of the transpiration stream is the differential in humidity between the air inside the leaf and the air outside. If both are close to 100%, there isn't any water loss.

The "dew point" is one way of doing this, other ways are the mist or fogging units that they use in commercial horticulture. A mist unit works from an "electronic leaf", this is basically 2 electrodes mounted on a plastic block, when there isn't any moisture on the sensor, no current flows between the electrodes and the mist is turned on. As soon as the surface of the sensor is wet, current flows and the mist turns off. On a day like today the mist would be coming on every couple of minutes, on a damp day in December it might not come on at all.

A fogging unit typically gives slightly better results, in this case the mist is extremely fine and gives both moisture and evaporative cooling. One problem with some cuttings in fogging units is that they don't actually "realise" that they are not connected to their parent plant, and for this reason don't form callus or new roots.

If you use the dew point method, like "Foxfish", you will be less prone to moulds and algae on the plant leaves etc.

Cheers Darrel
 

Michael W

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So essentially by having a high humidity environment the water want travel from the area of low water potential (the plant) to that of a higher water potential (the area outside of the plant) but instead the opposite way round and therefore keeping the plant 'moisturised'? And by Foxfish's dew point method your essentially eliminating the wind's or breeze outside which may otherwise change the water potential gradient?
 

dw1305

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Hi all,
So essentially by having a high humidity environment the water want travel from the area of low water potential (the plant) to that of a higher water potential (the area outside of the plant) but instead the opposite way round and therefore keeping the plant 'moisturised'?
Yes, although the water doesn't go in or out unless there is a water vapour gradient. Terrestrial plants need to lose water to drive the transpiration stream and keep photosynthesising. When the plant wilts it is because the stomatal guard cells have lost turgor (closing the stomata), this stops photosynthesis (no gas exchange) but limits water loss.
pitman10.png

From: <3. Terrestrial Ecosystem Modelling — geogg124 1.0 documentation>
And by Foxfish's dew point method your essentially eliminating the wind's or breeze outside which may otherwise change the water potential gradient?
It all depends upon relative humidity. If there is a constant exchange of air which isn't at 100% RH, the plant will lose water, but if all the air is at 100% RH air movement becomes irrelevant. Fogging units have fans to blow the fog about, but all the air is saturated with water so it doesn't cause water loss.

True aquatic plants can't make use of the transpiration stream, but use water pressure differential to drive water from the leaves and out through the stomata: <http://www.bio-web.dk/ole_pedersen/pdf/FB_1998_ch_12_196.pdf>. Floating, or emergent plants, have the best of both worlds, they have a transpiration stream, and access to unlimited water and aerial levels of CO2.

cheers Darrel
 

Samjpikey

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Interesting guys thanks for the information .Currently in my dsm the hygrometer reads 99% humidity (accuracy within 5%) . That doesn't change even during the photoperiod .
I do have a small gap along the back for venting.
So essentially if my hygrometer is accurate enough I shouldn't have to continue to 'mist' ?
What about introducing fresh co2 into the tank ? If so how often? If left open for say 15 mins the humidity will change, could it then need misting ?
Cheers
 

foxfish

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I don't think you need to open up the tank at all, the plants are producing C02, I have certainly left my tanks for weeks on end completely sealed.
The Victorians were very keen on bottle gardens & some fern displays were corked for years on end, so nothing new here LOL.
 

dw1305

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Hi all,
Currently in my dsm the hygrometer reads 99% humidity (accuracy within 5%) . That doesn't change even during the photoperiod . I do have a small gap along the back for venting. So essentially if my hygrometer is accurate enough I shouldn't have to continue to 'mist' ? What about introducing fresh co2 into the tank ? If so how often? If left open for say 15 mins the humidity will change, could it then need misting ?
Sounds fine, I wouldn't worry about CO2, any small gap will allow gas exchange. If you took the lid off for any length of time (more than a couple of minutes) I'd re-mist before closing the lid.

I should also have mentioned mosses, these don't have any water conducting tissues (xylem etc) and this makes the leaves (microphylls) very prone to damage from drying.

I've also found that you can still buy a "dew point" propagating cabinet via "Two Wests and Elliot". Still out well out of my price range however: <Two Wests Dewpoint Propagation Cabinet: Amazon.co.uk: Kitchen & Home>.

cheers Darrel
 

Samjpikey

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Sounds good guys , looks like I will just be leaving it alone from now on .
I did read an article somewhere where an old bloke found a bottle garden which had been stuck in his attic air right for 10's of years and its still thriving , I will have a dig and post the link .
Cheers
 
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