Leca as substrate for terrarium -- algae?

[MJG]

I am starting a big terrarium build. I'm planning on using a 4" layer of leca in the drainage area. A mistking system will water daily from above. I'm installing a drain about 2.5" up from the bottom of the terrarium. So 2.5" of the leca will be submerged all of the time with some water replacement via the sprinklers and drain. The other 1.5 inches of leca above will keep the substrate (above that) about from sitting in the water. It also will hopefully allow humidity to wick up.

Do you think I'm going to have a problem with algae buildup on the lowermost 2.5 " of leca? And if that happens, how on earth would I get rid of it?

I've read above others using leca as a drainage layer but haven't read anything about dealing with algae.

Thanks!

	Mistking Looking for a misting system? Look no further. Automated misting systems from MistKing are used by multitude of plant enthusiasts and are perfect for Orchids. Systems feature run dry pumps, ZipDrip valve, adjustable black nozzles, per second control! Automatically mist one growing shelf or a greenhouse full of Orchids. See MistKing testimonials

[estación seca]

You will have algae. There aren't any easy ways of removing it. Why do you want that deep a layer of LECA? Are you planning on having plants rooted into the LECA layer?

[MJG]

The terrarium is big -- 36"h x 36"w x 18"d. I was planning on maintaining 2.5" of water in the bottom for humidity. 1.5" of additional leca sits on that, but not submerged in water. A mesh barrier on top of that. And then about 2" of organic mix on top of that.

The organic layer is where I would plant some terrestrial plants, but most of my orchids with be mounted on cork and branches.

I don't intend to let anything grow down into the leca. The wet leca is for humidity. The extra 1.5" of leca above that is so that the organic layer isn't sitting directly on top of the wet leca. It's intended to keep the organic layer from being sodden all the time.

[estación seca]

A half inch of water in the bottom would give the same humidity as 2.5". Do you need more than one layer of LECA below the level of your drain? Evaporation and humidity are proportional to the surface area, not the water volume. Having a very shallow LECA layer would give you more growing volume above, which is what every terrarist wishes they had more of. Raising humidity in terraria is generally not a problem.

[MJG]

You're making me revisit this, which is a good thing. I came up with my plan after reading about others' vivarium builds on blogs and websites. NEHERP is also a great resource for vivarium builds. They have some instructional articles online that are helpful.

It seems that for the bottom wet layer people either use raised eggcrate with freestanding water underneath or a layer of leca. NEHERP recommends leca. They say that the other purpose of this layer, besides humidity, is to allow builup of beneficial bacteria. Leca provides more surface area for that than does eggcrate.

In revisiting NEHERP's articles just now, they recommend 3" total of leca, with the drain placed 1/4 to 1/2 the way up. But they say to vary that with the size of the vivarium. I think it was the large size of my enclosure (plus my fear of drilling glass so close to the bottom of the tank) that led me to my leca layer sizes of 2.5" wet plus 1.5" dry. I don't mind losing an inch or so of growing height in a 36" tall vivarium.

I could cut the wet layer back to 1.5", and perhaps I should, but I still worry about algae control. Also, you are certainly right about evaporation being proportional to surface area. I am clueless, though, about how much evaporation will happen every day. I'm going to be running exhaust fans that suck air out of the enclosure.

[Ray]

I learned this recently: A few drops of Dawn liquid dishwashing liquid in the water mostly prevents algae.

[MJG]

Originally Posted by Ray

I learned this recently: A few drops of Dawn liquid dishwashing liquid in the water mostly prevents algae.

That's helpful, and would be gentler than physan. How much do you use per parts of water?

[MJG]

Or probably a better way of asking -- how many drops per gallon?

[Ray]

Originally Posted by MJG

That's helpful, and would be gentler than physan. How much do you use per parts of water?

I have no idea. I have a cylindrical vase that’s about 8-9” in diameter, with about 1/2” water + LECA. I added a small squirt from the bottle.

It has been about 5 months and I’m just beginning to see a little algae.

[MJG]

ES and DC, last night I went back and read (and reread) a lot of material on terrarium building. You've both talked me down from creating a 2.5" sloshy layer of leca down to about 1.25". Thanks!!!!! I think you saved me from an ugly mistake.

I also went back and edited some of my earlier improper terminology in this post.

If this were a true closed-system wardian case type of setup, then I think ES's recommendation to use 0.5" would be spot-on. My system won't be entirely closed. I'll be adding new water periodically from overhead, I'll be running exhaust fans, and so I do think I need a little more water in case the drainage layer falls below my 1.25" level as things evaporate.

DC, you mentioned this...I do plan to using mesh over the 3" of leca, and then the actual substrate for planting on top of that.

I still have the question of algae. Ray's suggestion of Dawn detergent is helpful. However my situation is different from his terrarium. I would need to periodically introduce new soap and disperse it into the leca in the drainage layer. I haven't worked out how to do that yet.

I've read above people blacking out the drainage/false bottom area beside they say algae won't grow without a light source. That might work but I want to be able to see the water level.

Hmm. I'm still inviting some brainstorming on the algae issue.