Rock Wool + LECA

[PeteM]

Well... It's a German brand and apparently the company no longer exists, so who's to know that someone is selling a knock-off with that label?

I have seen changes in the product labeled as "Hydroton", so again I'll ask, who's to know if it's a manufacturing change or a product substitution?

If one was to purchase clay balls today, which brand do you recommend?

 

[Happypaphy7]

Ray- Good question. hmmm Do you know when the company in Germany stopped the production of hydroton?
Maybe it's possible that someone was selling whatever's left in the warehouse or from overstock from the past before the company stopped manufacturing?

 

[Russ1992]

I have the "Modern Moisture Retentive Mix" from Orchids Limited that contains rockwool mixed with coarse large perlite. Would the perlite work the same way as the LECA to provide some aeration? I want to move all of my paphs to this mix once they quit blooming so that I don't have to think about it as much as I do when they are in a bark mix, and I also worry about the ones I have in pure sphagnum being too moist.

First off I would only experiment on a few plants whenever changing your culture unless you have multiples of the same kind or you are willing to potentially have them sacrificed to the orchid gods above.

Secondly, Rockwool holds more water than Sphagnum moss as does Perlite in comparison to clay pellets (this is at least the case with Hydroton). So, proceed with caution.

 

[Ray]

If one was to purchase clay balls today, which brand do you recommend?

There are just so many out there, and many of them are only distributed over a narrow geographic range (freight cost), that it's hard to make a recommendation.

In my case, the one hydroponics shop I'm aware of in Wilmington NC carries Cyco Hydroclay, which appears to be quite clean.

I purchased a bag of Gardenera expanded clay pellets back in 2021. They were made in Ukraine and were cheap (no longer), and shaped more like a medicine capsule, rather than being spherical. They were pretty good, too.

Ray- Good question. hmmm Do you know when the company in Germany stopped the production of hydroton?
Maybe it's possible that someone was selling whatever's left in the warehouse or from overstock from the past before the company stopped manufacturing?

Sorry, I do not know.

Back in 2020, folks sent me samples of a variety of products and I did some comparative testing. Hydroton was one, taken from a bag I had on hand.

First off I would only experiment on a few plants whenever changing your culture unless you have multiples of the same kind or you are willing to potentially have them sacrificed to the orchid gods above.

Secondly, Rockwool holds more water than Sphagnum moss as does Perlite in comparison to clay pellets (this is at least the case with Hydroton). So, proceed with caution.

Water retention in LECA is quite variable, due to differences in raw materials and production, leading to differing porosity size, distribution, communication, etc. However, because the stuff tends to wick and absorb pretty well, most of the water is held within the particles, rather than at the surface.

I believe that the quality of a potting medium I think about most is the volume of open spaces. If it's big enough, the water holding capacity merely sets the required frequency of watering, the more often, the better.

It also seems that different plants have different free air volume, or possibly air-to-water ratio requirements.

 

[terryros]

Well... It's a German brand and apparently the company no longer exists, so who's to know that someone is selling a knock-off with that label?

I have seen changes in the product labeled as "Hydroton", so again I'll ask, who's to know if it's a manufacturing change or a product substitution?

You did the testing on the group of LECA products - is there anything right now that you trust in the group or is it all uncertain?

 

[Ray]

Terry,

My conclusion is that any of them is acceptable, but none is to be trusted for cleanliness, even batch to batch, so do an extensive presoak.

The Cyco Hydroclay I have seems clean, but it still gets a soak.

 

[ScientistKen]

Ray,

I get mixed results using Hydroton mixed with rockwool for Phrags. I think soaking would be a benefit. I remember a speaker saying to soak in acidified water. Do you soak in RO water or in acidified water or something else? I also notice some issues with crystals forming on the pebbles and also pH raising over time.

I remember you saying that the geometry of the spheres maximizes air ratio. That has stuck with me. Definitely a plus.

 

[Ray]

White crystals forming on the LECA is either accumulated minerals or manufacturing residues. If they are acicular and make the pellets look “fuzzy”, it’s likely the latter. Either way, more humidity and/or more watering is a good idea.

Back in the days of PrimeAgra, the binders they used in manufacturing were sodium salts, so I added calcium nitrate and/or Epsom Salts to the soak water to “extract it faster”, figuring it would be a process similar to a water softener - salt coming out of the substrate, replacing the Ca and Mg in the water, but we dump the water and keep the now-fertilized substrate. Since then, I don’t know what binders are used by each manufacturer, just use plain water, and have found that length of soak with repeated water changes is more effective than any additive at extracting the residues.

I suspect the purer the soak water, the better, but I’ve always just used my well water in PA and municipal water here, which is pretty pure, aside from the lime they add to “sweeten” it.

I don’t know why one would add an acid. Every LECA I’ve ever seen, when soaked, yielded an initial pH between 5 & 7 in the soak water.

I was high on “Grow Stones”, as it was basically synthetic perlite made from recycled glass, but it was particularly alkaline, so they tried “passivating” the surface via an acid bath. That works, but only temporarily.

 

[Heather]

Thanks for all this. I’m interested in more growdan info as the two Phrags I have in it seem happy.

We have some LECA type stuff at work. I’ll snap a pic today. I’ve always looked down my nose at it as I have high Prime Agra standards but now I’m curious to know more about it.