Yes. Clay. I love this stuff. I have noticed that in pots where I use 50% arcillite, 25% LFS, and 25% bark & charcoal as the medium, with a 1/4th inch top dressing of Sphagnum, I can have near-instantaneous drainage , however, it has been my experience that it does not dry out any faster than pure LFS. A tablespoon (if that) of peat was added to bind it all together, but this tablespoon was distributed between three six-inch pots so any effect it had on water retention is very likely negligible. In retrospect, I don't believe I needed to add it at all. A half inch layer of Arcillite (excluded in the medium ratio) was placed on the bottom. I also added Aragonite and crushed Scallop shell equal to 10% of the media volume. That's irrelevant but figured I'd throw that out there just to include all the details. I originally did this just for N. campanulata, because I was trying to mimic the rocky, free draining habitat that I have been told "dries" (in the sense that we use it in this hobby, in other words not literally with the exception of one plant's requirements OTTOMH ) rapidly and is replenished via rainfall just as rapidly. To be honest, I thought the mixture I used would dry too rapidly, which is why I added a 1/4th inch layer of Sphagnum, but I was wrong. However, the plants aren't complaining about the watering schedule as of yet. Although, with my limited experience with this species, that could change. Given the anecdotal ease of this species, I doubt it will is negatively affecting them, although doing without (but probably at the cost of watering every three days rather than five) would probably be better or have no effect at all.
I believe Lightweight Expanded Clay Aggregate (LECA) has been overlooked in this hobby, or just unknown about as an option. The very word "Clay" strikes skepticism in some, because when we normally think of clay, we normally think of minerals, and when we think of minerals in this hobby, many people think of the compost bin. The important factor is that this clay has been baked. Arcillite in particular comes from Montmorillonite, but other LECA products can come from other sources. You are all most likely familiar with Arcillite from Schultz's Profile, and as the small rocks that come in pre-mixed orchid media. My original use of this was by dumping the orchid mix in a bucket of RO water, swishing it around, and scooping the Arcillite off of the bottom. I did not expect to get such pleasing results, to be honest, which is why I didn't go out and buy liters of it online. Unfortunately, I have not been able to source a source (hahaha) for the large/coarse grade Arcillite found in pre-packaged orchid mixes. I have only been able to find the small grade Profile/Turface, which I will address later.
A great alternative to this is other LECA products, such as Hyrodroton and other miscellaneous brands and generics or particularly PrimeAgra. I have done no comparisons, but anecdotal evidence and a test made by a retailer(which isn't a good source, at all, considering it could be biased and thus fake, but there's no reason to believe or disbelieve that) shows that it has superior absorption capacity compared to other available brands of LECA, HOWEVER there are other, lighter LECA products to be had, apparently at the sacrifice of wicking capacity. The superior absorption capacity in PrimeAgra has been contributed to the smoother shape of the newer version versus the rough, irregular shape of the original that I like so much. That's unfortunate that you can't have both, but c'est la vie. The weight difference seems to be irrelevant, as it's really not heavy to begin with, and we aren't using 10 gallon containers, so our primary concern is having a coarse, airy, very free-draining media that holds water well. With some species that like it a bit less moist, using a different brand would be a perfect fit. Here is that comparison:http://www.firstrays.com/PrimeAgra/compare.htm
What I liked so much about the Arcillite found in the orchid mix was the irregular, natural shapes. I felt that they "held together" the media better than the spherical LECA products (hypothetically, as I have never used spherical products, but it's a logical hypothesis) that I knew about from pictures of hydroponics. The increased surface area would also harbor plenty of space for bacteria to grow, which could help our plants by breaking down decaying matter (and our fertilizers for those of us so inclined) into nitrate.Although smoother, more uniform brands would also have a lot of surface area. I just haven't been able to find a large/coarse grade of LECA or Arcillite that is the texture of that found in Schultz's orchid mix, and I doubt Schult'z will sell me anything less than a truckload of the stuff (if they have time for that, at all!) Speaking of which, I should mention the high CEC capacity that I originally learned of when using this for an aquarium. It absorbs nutrients and slowly releases them. Your media would, it's self, become a time-release fertilizing mechanism, absorbing some of the nutrients added monthly or bi-monthly, and releasing them slowly for the plant to utilize.
Now. Let's talk about Profile and Turface. Usually it's abbreviated APS for short, and still people don't know what it is when explained. This is an EXCELLENT substitute for Perlite Our floating friend! It has several benefits, and one draw back. The drawback is really a double edged sword. On one hand, it's heavier than perlite. I believe the standard Schultz's perlite bag is 8 quarts, and a more or less equal sized bag of Profile is ten pounds. This is noticeably heavier, however, in the relatively small pots we use, it's negligible and really won't matter when you consider the weight of pure LFS when wet. Still lighter than that popular, tried-and-true media. The benefit of this is that it does NOT float. When added to water, it's heavy enough to sink but light enough so that slowly moving your hand through the water is enough to disturb the bed of profile. We all love perlite, but we hate the fact that it float. What else do we have about it? We hate the stark-white color. Especially when it turns from stark-white to bright green... Profile, OTOH, is an natural beige when dry, and an attractive brown when wet. Profile is much, mush dustier than Perlite. Profoundly so. Do not believe the bag LECA is also an excellent substitue for Lava rock, because let's face it, all lava is not created equal and I'd rather not have it leach something when I can use something I KNOW will not leach something. Theoretically, the LECA is easier on the roots versus the rough lava when it comes time to repot. It's also a great substitute for pumice for the reasons cited above for perlite.
Another excellent benefit of LECA is that you can use it over, and over, and over. If you are a hygienic grower, you can bake it before re-use. I don't know if using an pressure cooker for the overly-paranoid is advisable. Personally I'd be afraid the air in the LECA would expand and blow up. It's certainly not necessary, and if you're overly-paranoid about disease, instead of potentially blowing yourself up, you can just soak it in a diluted chlorine solution and allow to thoroughly dry before re-use. A soaking or two in RO water after that is good, to be on the safe side. Personally, I wouldn't bother. Of course you know what they say... you plant something in another's medium and you're planting it with all of the plant's that medium has been used with! Perlite is re-usable, however it would be difficult as a lot of the ingredients we use float... and so does the perlite! I don't know anyone with enough time, patience, and a pocketbook tight enough to bother with separating perlite for re-use. However, dumping your media in a container of water , swishing it around, and allowing the LECA to sink and the other matter to float would be a VERY easy way to separate the ingredients and save the LECA for later use. Like Perlite, LECA is does not buffer and does not leach anything except what you, the grower, purposely adds to the media. If you don't use pure water, this could be bad, but you should be using pure water anyway. I already explained the benefits of the cation exchange capacity in regards to fertilization via the roots.
Now. Akadama! This is a clay/ clay-like mineral used in bonsai, and as far as I know it comes in baked and raw-forms, as well as hard forms from deeper below the earth versus soft, crumbly forms from closer to the surface. This is mainly used in Japan, and I couldn't find much on it at all. It's expensive compared to LECA, but I thought I would include it since we are talking about clay and not just LECA. Kanuma is another clay-like mineral that seems to lower the PH, however I do not know if it leaches anything other than what is purposely added and the absorbed. Besides, it's ugly These are really prohibitively expensive, unless you just want to be cool and use exotic ingredients from the far east. Of course, there may be benefits I am unaware of that just may justify the cost in our situation! Doubt it!
I have heard of burnt clay from Cindy. No idea what differentiates it from clay that has been baked, like Terra Cotta. If its the same, then it, too, would be a viable media option for all Nepenthes provided it does not leach minerals or buffer the way Terra Cotta doesn't. Unless it's expanded, however, it would not have the benefits above. A few Nepenthes, such as N. rajah and N. northiana, have been known to grow superbly with clay components (Rob Cantley's N. rajah appear to grow in primarily, if not completely, clay) as some of these plants grow in serpentine and ultramafic media in the wild. We've all seen the pictures of these counter-intuitive environments and the amazing plants they support! Just now I paid an overdue visit to the fLORA nepenthacaea forums, to find out the N. klossii is found growing on/in clay! Fascinating! Unless you know exactly what you're doing, I can not recommend using just any clay. I certainly wouldn't use any unless I bought it from someone who has used clay from the same source as is being sold to you for a few years, and a nice plant to prove it! Unless you have expendable plants of course. Like lava rock, all clay is not created equally.
I will undoubtedly play around with LECA in the near future. I believe that with a dedicated grower to water religiously, that a mix of 75% coarse LECA and 25% LFS (honestly, I'm not sure if 25% peat would work or not) would be an IDEAL media. Practically growing in nothing. It really wouldn't need to be replaced, and repotting would depend only on the size of the plant, and not the decomposition of the media. Repotting a plant every year to every other year, even if it's put back in the same pot, usually invigorates the plant after stress subsides because of the fresh media versus the old crap. With this, theoretically, you could enjoy the benefits of a vigorous plant without having to re-invigorate it with fresh media every to every other year and thus initially stressing it out by disturbing the roots! The increased air flow, and just-moist-enough media would also encourage a more extensive root system, resulting in a plant that is better equipped to handle a skipped watering in case you forget or are unable for some reason. This also results in a firmer "anchor" for larger plants, AND increases nutrient uptake capacity!
I hope you have found this rather windy post interesting, and I hope some of you experiment for yourself and report your findings. Few people use this substance, so it would be nice to have more information on it in our particular hobby. It seems to be an ideal media ingredient, at least in my experience and conditions. The above theories could be applied to other Genera, but my primary interest is in Nepenthes. I have used Profile for other genera (Sarracenia, Dionaea, Pinguicula, and Drosera) without problems. Most of the theories could be applied to Heliamphora, since their culture is so very similar to Nepenthes culture. I see no reason why not.