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Old 06-29-2020, 01:42 AM
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Default puzzling, persistent substrate dampness

I'm wondering if there is an obvious explanation that I'm just not seeing to my seemingly constantly damp substrate. I think that's the reason for the failure of a Selaginella uncinata and S. kraussiana and the reason my Ficus thunbergii went from establishing well at first to now gradually losing leaves and becoming chlorotic.

Specs: I have an Exo Terra large tall (36x18x24) that's been set up for maybe six or seven months now. I used the Growstone-like medium as a drainage layer, topped with window screening-type separator (not landscape fabric), and then the ABG mix + calcined clay pre-blended by the vendor. I soaked the substrate briefly in distilled water prior to laying it into the tank. I have glass insert covers over the stock screen top to help hold in humidity (they leave about an inch of screen strip to vent) and am using an LED panel from Spectral Designs. I have one multi-speed 2" computer fan to help circulate the air, on "low". The glass never fogs, and the hygrometer (just the cheap-o typical ones the size of a pack of gum that reads temp and humidity) never reads very high humidity except for overnight. It's in an abode with central air, so the room temps stay in the low 70s for the most part and the ambient room humidity in the winter sucks. I must get decent air exchange, though, because the tank's apparent dampness never seems to be very high during the day or fog up the glass. You would think that would help to dry the substrate, but...?

I don't have a water feature, and I mist by hand a couple of times a day, just enough to wet the wood and epiphytes. The misting isn't enough to rain on to the substrate in any meaningful amount. I rarely put water in the drainage layer because it doesn't seem to raise humidity, and when I have, the water level is well below the substrate barrier.

The trouble is, the substrate has never needed moistening since I put it in at the start. As this is a terrarium (no animals), I do use an eyedropper to occasionally dose the root zones of the few terrestrials in there (so far) with orchid or Tillandsia fertilizer. However, this doesn't happen often enough that it would explain the wetness. I don't understand why it's staying damp, and assume that's the reason the plants mentioned above failed. There are a couple of others that are struggling, though the rest are doing ok (not great, but ok).

Was soaking the substrate at the start ill-advised? Is the calcined clay contributing to this issue? (I've been trying to read through the related thread about its use as a substrate or drainage layer but the pictures come through so large on my screen that it's hard to follow.) Is it likely the dampness isn't the issue? I'm going to try more moisture-loving species next time I'm ready to add more terrestrials to see how that pans out. In the meantime, I would like to save the Ficus and prevent other plant failures. I am assuming it's a root issue since root and foliar feeding of the plant hasn't averted progression of the chlorosis. I know with temperate garden plants that poor root health can result in foliage malnourishment.

It's still a work-in-progress with regards to setup/planting, but the picture is fairly recent. I included a couple of the construction process. There are a couple pieces of wood that touch the base (at the time, I was foolishly planning on a water feature and a less terrestrial base). I doubt any wicking they're doing is causing this because the above-ground parts are never damp and you'd think that all this time wicking would have measurably dried things out.

What am I missing?
Attached Images
File Type: jpg tank Exo Terra Large Tall 16.jpg (95.4 KB, 34 views)
File Type: jpg tank Exo Terra Large Tall 3m.jpg (84.5 KB, 23 views)
File Type: jpg tank Exo Terra Large Tall 7h.jpg (72.5 KB, 22 views)
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Old 06-29-2020, 03:42 AM
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Default Re: puzzling, persistent substrate dampness

My first thought is wicking. It almost has to be something wicking.
Wicking can actually move a lot of water, faster than you might think. It moves so much water, it has inspired an entire method of pump free hydroponic farming.

I used the Growstone-like medium as a drainage layer

More details on this please. Is that the white stuff at the front, bottom, of the viv? If so, and if I'm seeing this right, I believe that's your culprit. I see small white particles touching the bottom of the vivarium, and touching the ABG. To my eye, those particles look way to small to be an effective drainage layer. Large particles, like pepples, are big enough that the surface tension of the water breaks before real wicking can really develop. The smaller the particle, the smaller the space between particles. That means the surface tension of the water can easily jump from particle to particle, lifting water ever upwards into the ABG mix. Now, you said growstone like media. To me that means something like LECA or Hydroton. That means porous. Porous holds more water than the pebbles we discussed. The fact that it's holding more water, helps keep everything wet, and further enhances the wicking action.

I believe you did something I did once upon a time. In using too fine a material for part or all of your drainage layer, I created a very efficient, completely power free, hydroponics system! I made the reverse of what I wanted to do. I did it using Turface, or calcined clay, which I've come to believe is a very poor choice for a drainage layer. I found that only a one inch strip of turface, used to hide the eggcrate/screen drainage layer, pulled several gallons of water out of the bottom and up into the substrate. It emptied the false bottom overnight.

If my assumptions are correct, I'm pretty sure it's all about that drainage layer being too fine a particle, and possibly porosity adding to the problem.
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Last edited by Pumilo; 06-29-2020 at 03:55 AM. Reason: clarification
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Old 06-29-2020, 11:15 AM
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Default Re: puzzling, persistent substrate dampness

Nice to see a fellow Maryland'er

I agree with Pumilo that if your substrate is wet its because of wicking. I have been doing an experiment lately exploring different drainage layer options. What I found is even gravels not designed to absorb water (such as pea gravel and marble chip) will wick water. I am assuming your 'growstone like' gravel is designed to absorb water so it will definitely wick.

Fortunately the solution is very doable. You mention that you add water occasionally to your drainage layer. Just stop doing that. Also you will likely want to siphon out any water already in there (assuming you do not have a drain). You will need to disturb a corner of the viv but otherwise it shouldn't be too traumatic to your setup. If it were me I would tilt the whole viv and prop it up at a an angle to get as much out as possible.

Without water in your base or even just moving the water line down as far as possible you will dry your substrate substantially better. Regular misting combined with normal humidity should be fine for all terrestrial plants we are growing. Since you are hand misting if you notice any plant needs more attention you could always mist that plant a little more.

Hopefully this helps.
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Old 06-29-2020, 05:02 PM
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Default Re: puzzling, persistent substrate dampness

Yeah, wicking was what I was assuming also. The puzzling thing for me is that I have hardly used the drainage layer as a water reservoir (especially since I noticed the trend of damp substrate awhile ago) and I definitely haven't deliberately put any water down in that layer for over a month (possibly even two...these weird days are messing with my sense of time).

I understand the idea behind the wicking physics of smaller particles though - capillary action and all that - though I admit I didn't give it much thought. You're right - these are on the small side relative to something like LECA balls. I'm just perplexed by the fact that, given how relatively little input the base has had, water-wise, why it hasn't dried out measurably in the past several months since being installed. Especially since the ambient humidity of the tank seems fairly low during the day (about 30-40% winter, 50-60% summer). Did I accidentally create some sort of self-contained system of water cycling just in the substrate and drainage layer (in other words, insufficient evaporation), where the initially soaked substrate slowly drip-drains into the drainage layer, only to be re-wicked back into the substrate?

The Growstone I've used for other things comes in multiple particle sizes (around a quarter inch up to an inch or more), and while that's just one brand of the stuff, I swear everything I see that looks like this is all the same material, just sold under different brands. If memory serves, it's recycled glass, and resembles pumice or a fine lava rock but is lighter in weight. In other applications, I've used the finer stuff as a potting soil amendment for succulent containers. It doesn't float like perlite does over time, and I think it's pH neutral given its composition. Anyway, the particular material I used was from Josh's Frogs (https://www.joshsfrogs.com/josh-s-fr...r-1-quart.html), though I have some unused from NEHerp that appears to be the same exact stuff, just the larger ~1" grade. Ditto Black Jungle, though it's a different color.

I did include a siphoning "port" when I installed the drainage layer - it's just a short vertical section of corrugated tubing that I can stick a turkey baster into in the front right corner - easy to access. Trouble is, there's nothing to siphon out - no free water. Presumably that's because it's locked-up where I don't want it. I do not have a drilled drain because I'm using the tank as-is and am not experienced or equipped (or ready to try) in drilling glass.

So, I'm wondering what the best approach is going forward. Do I pull out everything (terrestrial) and re-do the drainage layer? (With what, if I don't use suspended egg crate...LECA or...? Or is propped-up egg crate best?) Or just work with what I've got and use emergent aquatics, in the assumption that it's staying damp enough that they should prosper w/out free water for their roots? I do have a Hemigraphis repanda in there that initially did well (may have just been a "thank you for taking me out of that tiny pot" growth spurt) and is now looking so-so.

I realize the trouble I'm willing to go through to fix this is up to me, but outside of that, are there other reasons to either re-do things or adapt the plant palette instead? I'm assuming the substrate mix itself isn't an issue, considering how prevalent it seems to be in this hobby.

Interestingly, the Growstone mixed into my succulent soil does not seem to hold moisture - if anything, I think it dries the mix out faster (a bonus in that case, certainly). When used as a topdress on some of those pots, it also seems to dry quickly - perhaps the better air circulation?
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Old 06-29-2020, 06:14 PM
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Default Re: puzzling, persistent substrate dampness

If there is no free water in the bottom of your tank then there is no real wicking going on. I feel like this is likely not your issue.

Plants might die from lots of other factors, insufficient light, not enough nutrients or the wrong kind of nutrients or too much nutrients, or they were just plain unhealthy to begin with etc. What makes you think the substrate is too damp? Your more recent picture shows a number of plants in the substrate, are those plants doing ok now or are there problems with their growth?
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Old 06-29-2020, 11:10 PM
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Default Re: puzzling, persistent substrate dampness

Well, unless there's some localized wicking from wet substrate seeping moisture into the drainage layer and back again in an endless cycle. Still, I don't understand why the relatively low ambient humidity of the tank (and definitely outside the tank earlier this year from the central air) hasn't depleted a significant amount of that moisture since what I'm adding doesn't amount to much.

I don't doubt that I have root issues on a few things due to their care prior to planting. I have certainly over- and under-watered my share of houseplants. Several have declined after planting, though, and I think lighting issues would have manifested differently - darkening leaves with perhaps exacerbated shed of older growth when under-lit and bleached new growth with smaller-than normal leaves if over-lit. I can look up the specs of the light fixture if it would help, though.

Given the popularity of the component ingredients (and ABG mix in general), I assume pH is not a factor; I know that pH can influence nutrient availability. I'm using distilled water, though the fertilizer water is mixed with tap that might be a bit hard. The occasional (once or twice a month, tops) fertilizer has generated improvements in foliage on plants seem healthy. It does not seem to help those that are struggling. Since I doubt nutrient deficiencies (mainly chlorosis) in the foliage would manifest from insufficient lighting alone, I'm assuming it's a root issue - the roots are not able to absorb the nutrients present. And that usually means too much or too little water; given these circumstances, I'm guessing too much.

I can feel the dampness of the substrate, and it stays dark in color, unlike the lighter coloration of the component ingredients when dry (plus several unused dry bags in storage waiting for other projects). It easily sticks to my skin when lightly pressed - especially the clay bits - though it isn't so wet I can squeeze any water out of it.

The plants still in the substrate are a mixed bag. Some are doing acceptably well, while others are looking piqued and a few have simply died.

Plants doing ok (not necessarily spectacular, but at least ok):
Hemigraphis repanda
Pilea peperomioides
Syngonium wendlandii (or rayii)
Peperomia metallica (or similar)
Philodendron Wend Imbe, from a cutting
Hemionitis arifolia
Pilea involucrata Moon Valley (or similar) from cuttings which have since rooted
Rhaphidophora cryptantha (from a plant I had acquired over a year ago and which slowly declined; I eventually took a few cuttings and the rest was a lost cause; there are four cuttings in the tank, one of which is doing far better than the rest and shingling up a piece of wood, albeit slow and with leaves still smaller than a dime)

Plants not doing well or declining, but not dead yet; some merely malnourished-looking:
Episcia NOID
Peperomia Rana Verde cutting
Ficus thunbergii (pumila Quercifolia) - grew very well at first, rooted onto background (foam + silicone + fine substrate covering), then began a steady decline losing leaves, chlorosis, and minimal new growth
Ficus Panama (took longer to get chlorotic than the other Ficus; not planted in the "ground" but rather in a substrate-filled planter pocket of a net pot in the background about halfway up
Adiantum Lace Lady (or Micropinnulum)
Elaphoglossum peltatum (though this wasn't a stellar specimen to begin with and hasn't been in the tank as long)
Gloxinella lindeniana (maybe it's going dormant? has lost lower leaves and is more floppy and a bit less richly colored than it used to be)

Full-on died:
Piper parmatum (this one may have had issues prior to this, but I was hoping this might serve to rehab it a bit with better humidity than where it was growing...nope; new leaves at first but steady decline afterwards, and the leaves never even reached full size)
Selaginella uncinata and S. kraussiana
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Old 06-29-2020, 11:23 PM
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Default Re: puzzling, persistent substrate dampness

Greetings,

If you have no drainage outlet and you are using hard water for the fertilizer feedings you are likely going to be building-up salt in your substrate - particularly since you don't see any water draining into the bottom. This may not be your immediate problem if this is a young viv - but it will be an issue over time.

Your current problem could also be an issue with young substrate. Freshly mixed substrates that use un-composted organic components need a period of weeks to months to mature because the first stages of decomposition require nitrogen before they begin releasing nitrogen. This means fresh organics compete with plants for nutrients. Not sure if this is your issue but it could be - especially if you planted densely at the start.
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Old 06-29-2020, 11:59 PM
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Default Re: puzzling, persistent substrate dampness

Greetings!

Terrestrial plantings are still fairly sparse (both at the start and currently), but this is an interesting idea. I imagine I do need to stock it with springtails - there are a few, but nowhere near the levels they probably should be - and that might help with nutrient cycling. (There has been very little in the way of mushrooms or visible fungi, if that means anything.) I was using fertilizer as I have no other sources of input (no animals) of nutrients. Since it's epiphyte fertilizer (orchids or tillies, depending on what I'm doing with it beforehand) it's probably lower-dose on some minerals than average, and it is urea-free. The fertilizer use is quite minimal...we're talking maybe a small pipette/eyedropper full per plant at most, just to dose it in the immediate vicinity of its roots. I get that it's a fairly closed system but I'd be surprised that it's going to be an issue for some time IF the plant roots are healthy enough to make use of the nutrients.

Still, I'll certainly keep it in mind. Nitrogen tie-up does make sense given what I know about fresh vs. aged wood chip use outdoors in the garden (for example), though the interveinal chlorosis I'm seeing (esp. on the Ficus thunbergii) suggests iron or magnesium deficiency instead of nitrogen. (The off-color Episcia and Peperomia certainly could be nitrogen, though I would have thought a temporary fix from the added ready-to-absorb N in the epiphyte fert. would alleviate that.)

Someday I'll graduate to drained setups! Alas, it'll be awhile.

Since I'm still fairly new to terraria, I'm curious...is it normal to never have to water your terrestrial plants? Has anyone else had substrate never dry out to that point (if wicking weren't the issue)? Speaking of, do we still think this is wicking? Think I should redo the drainage layer or might a different plant selection (some emergent aquatics, perhaps) work out best?
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Old 07-08-2020, 04:52 PM
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Beautiful vivarium. Some people get that placement of driftwood just right.
On a side note I spent a week on the Delmarva Peninsula last summer (yes, Ocean City) and I absolutely loved it. Beautiful beaches and blue crabs galore, but I was amazed by all the beautiful farmland right outside Ocean City. Naturally I went exploring and found a pond/swamp habitat. Huge bald cypress trees, Crepe Myrtles, those magnolia trees with the leaves that don't rot after they fall off, and blue spotted sunfish. Unreal to think that exists just 360 or so miles from my house.
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Old 07-09-2020, 05:25 AM
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Default Re: puzzling, persistent substrate dampness

I'm a little hung up on a couple of things I read here. 1) Two species of Selaginella die from moist substrate (WTF?!?!?!) 2) Borosilicate glass has neutral pH (WTF?!?!?!?) 3) Growstone is dry (WTF?!?!?)

None of these square with my experiences. Specifically, 1) the best way to kill Selaginella is with drought. Although most plants from high-precip areas do not like alkaline conditions, they like (need...) acid. So an alkaline bath might also work for killing Selaginella (I've never tried, I favor them). 2) Borosilicate glass is alkaline as hell. You have to treat it like Portland cement - rinse it for weeks, or (dumb with cement, fine with glass) acid-bath it. Been there done that, hot tub test strips and all. 3) The wicking and water-holding capacity of Growstone is very high. It floats like a cork at first due to the extreme degree of internal vesiculation; but once it saturates it will sink (barely). And I think to get it truly dry you'd need to oven-bake it.

Given these thoughts, do you have any insights into what might be going wrong with your viv? E.g., your Fe / Mg deficiency chlorosis.

Good luck!
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Old 07-11-2020, 02:57 AM
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Default Re: puzzling, persistent substrate dampness

Dr. Manhattan - thanks! I see it with a more critical eye, but I appreciate the compliment. And yes, Maryland is a neat place horticulturally since we're not too far north to grow some southern plants (crepemyrtle, southern magnolia) and not too far south to grow some northern plants (lilac, cranberry - barely!). I'm certainly biased, but I like it!

jgragg - wtf indeed. I dunno, that's why I'm asking for opinions. I'll post some pics of the substrate material (not literally Growstone by name, but I strongly suspect it's the same stuff, just a different size grade and marketed by a different wholesaler), substrate, ailing plants.

Where did borosilicate glass come up? Or is that the only kind that can be recycled into such a product? I'm not up on enough chemistry for that. I used a pH probe on the substrate...didn't budge from 6.5, so either it's slightly acidic or the probe can't read it properly since it's much more porous than soil. It's ABG + calcined clay bits, so since it's promoted as a mainstream substrate, I gotta think it's not an issue.

I'd be relieved to learn the stuff died from drought - that's way easier to fix. When I pick up the substrate, though - still damp enough to stick to the skin without dusting off, and that's now, when I haven't filled the drainage layer in weeks and the only water input is my 2-3 x daily hand misting. I'm not heavy-handed with hit, I don't think. Perhaps I'm too used to soil gardening and judging terrarium substrate moisture levels is something I need to adjust to.

When I fertilize once or twice a month (perhaps more is needed, granted) with orchid/tilly stuff, which are complete and have micronutrients, the Ficus, Episcia, and a few others do not notably green-up. The Begonia vank. and a couple of Peperomias do. I haven't tried foliar-feeding the Ficus but I do make sure I squirt some of that fert. on its in-ground roots. Maybe the epiphyte fert. is too weak? Maybe the pH really is off and therefore not conducive to nutrient availability? Dunno.

I'm happy to be wrong on my assumptions of what's wrong, because it probably means an easier solution to the problem - though I'm back to square one in trying to figure out what that is. I've been in ornamental horticulture for 22 years, but that's with mostly temperate-outdoor, in-ground plants. Tropicals - especially those more touchy about environmental conditions - in an enclosed environment and a mostly-closed system is a bit of a learning curve. Despite having a growing collection of houseplants (including the aforementioned orchids and tillandsia) for most of that time, I still have a lot to learn. Lots of reading and video-watching; some experimenting, and some bumps along the way.

pics - some chlorosis and what's left of the Selag. (looks brighter in the pic than it is in person); drainage layer stuff (from NEHerp, I think) leftover in bag and what I think is the same stuff but larger from Josh's Frogs; layer in tank...visibly dry, at least; substrate
Attached Images
File Type: jpg Ficus Panama.jpg (72.1 KB, 9 views)
File Type: jpg Ficus pumila Quercifolia.jpg (82.6 KB, 8 views)
File Type: jpg Selaginella uncinata.jpg (79.5 KB, 8 views)
File Type: jpg drainage layer 2.jpg (43.3 KB, 5 views)
File Type: jpg drainage layer - JF.jpg (40.6 KB, 6 views)
File Type: jpg drainage layer.jpg (59.7 KB, 8 views)
File Type: jpg substrate layer.jpg (54.3 KB, 5 views)
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Old 07-13-2020, 03:11 PM
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Default Re: puzzling, persistent substrate dampness

Here's some useful info on the drainage layer material: https://hydrobuilder.com/learn/media-tips/

I don't know anything about J's Frogs but I sense a growing unease here about the balance they take between business on the one hand, and animal welfare & effective husbandry on the other. Meh, could just be me though, I could be wrong.

My guess is, you've got a remodel ahead of you, because you've got a design fail, because the material properties of your "drainage layer" have been misrepresented and/or not really understood. I think you need an air gap (a wick-break) between the glass and your organic substrate. Or, just chuck the glass and use Matala or egg crate on legs. Or, use Matala or egg crate, and keep the glass but mix it into an "ABG-ish" substrate. Just read that article I linked before putting the glass back into service.

I freely advise that I could be wrong here. But having played with that stuff some in the past, it's great for some uses and awful for others. You just have to understand its properties and behavior, and match the tool to the job. I found it best in planting mixes and situations where I discard my drain water, as it tends to lead to brown algae growth in recirc systems.

Good luck!
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