Preparing LECA Confusion...

[astrumes]

everyone!

I'm new to the hobby and the forum but I've learned so much by reading through what's here and on Ray's sight about semi-hydro. I'm excited to say that after some very big mistakes on my part I'm seeing lots of recovery from my plants but I have a question that I can't seem to get a good answer on.

I know a lot of people boil or bake their LECA before soaking and using the medium. I'm wondering is it necessary? Can I just rinse the LECA, then do just a soak in epsom salt for 24 hours? I don't know if that soaking process kills any bacteria but from what I read on Ray's site, this is what he does (though he also soaks it with calcium nitrate which I don't have on hand).

I did boil all my medium before I repotted but it was a huge pain and basically clogged up my sink. If Ray could give me some insight or a detailed step by step I would appreciate it! Unless of course, its just as you posted on your website.

Anyways, I appreciate any advice! Orchid fever has taken hold of me and I happen to live in a perfect place to grow!

[Ray]

LECA has been fired to a high temperature, sterilizing it. They might use non-potable water to quench it, but the stuff is often stored dry, so becoming "infected" with something that will affect your plants is very unlikely. There is no need to disinfect it, unless you are planning to reuse old material from other plants.

The soak with calcium nitrate and/or Epsom salts is to extract sodium-salt manufacturing residues, leaving some nutrients behind.

[astrumes]

Originally Posted by Ray

LECA has been fired to a high temperature, sterilizing it... There is no need to disinfect it, unless you are planning to reuse old material from other plants.

Thanks Ray! It's an honor btw! I'm so thankful for the s/h setup as well as the knowledge you make available, and how its helped with my otherwise brown thumbs. So glad to know I don't have to worry about preparing the new medium with heat.

My question now is how would you suggest preparing old, used medium? Would rinsing thoroughly to get rid of organic debris and baking the LECA at 500F do the trick or would you suggest boiling instead?

[Ray]

My process was to:

1. Let it dry thoroughly.
2. "Winnow" it in a breeze to remove most of the organic chaff.
3. Soak it in a solution containing Physan or chlorine bleach for a few days. I'm not convinced baking is sufficient disinfection, and I know boiling is not.
4. Rinse it thoroughly with copious amounts of fresh water.
5. Drain that, and let it dry.
6. If it looked crusty with mineral residues, i would often ditch it altogether, but i might soak it in the calcium nitrate/mag sulfate solution to try to extract some of it, then after more rinsing, add KelpMax and use it.

[estación seca]

Most of the mineral deposits on old clay are probably calcium and magnesium salts, right? What harm would there be in using that? They're hardly soluble.

[Ray]

Originally Posted by estación seca

Most of the mineral deposits on old clay are probably calcium and magnesium salts, right? What harm would there be in using that? They're hardly soluble.

The deposits are certainly calcium and magnesium based, but also contain organic "plaques" that can clog up the porosity, affecting the wicking action negatively.

Yes, they are hard to remove, but sometimes a good soak like I recommended will help loosen them up - don't ask my why or how; I always assumed acid would be needed. Maybe the organic stuff is holding the salts (carbonates?) to the substrate.

From a practical standpoint, LECA isn't that expensive, and I tended to throw away the top inch where all of the deposits occur, before prepping the rest for reuse.

[WaterWitchin]

Late to the party, as usual. I always soak LECA in a LOT of water (5 gallon bucket, completely covered with water) for at least 24 hours, occasionally flushing by sticking a running hose to bottom and letting water flow out top of bucket after stirring it like a witch's brew cauldron. Ten I dump into a couple of very large net plastic baskets I have, used mainly for growing pond plants. And rinse it some more with a hose.

I do this because depending on the LECA I purchase, some has had like an "oil slick" on top of water... when it does, I resoak at least 24 more hours. Starting with HOT water, then stick a hose down to bottom of bucket and let it run, forcing the yucky water over the top.

Depending on the LECA, some of it can have some pretty interesting process before it arrives to you. I don't want super weird oily chemicals on my orchids. Or myself, for that matter.

[Ray]

I don't know how much of this is done any longer, but some brands of LECA were manufactured using kerosene or diesel fuel as the binder for pelletizing the clay, as that would burn off in the firing process. Unfortunately, if the firing process was insufficient, there would be some residual oil in the pellets.