An additional point is that when you buffer with a high Tween 80 concentration, the resulting media is then much less prone to channeling. At least in my experience, if your buffering solution includes 100 ppm of Tween 80, the media will then retain significantly more water and channel significantly less, without ever having to add the Tween 80 again through the crop cycle.
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What @danielfp wrote about the neutral nature of non-ionic surfactants with CEC sites is spot on. And I would add that depending upon the coco brand you’re using, there’s no need to worry about sodium or chloride because they’re sufficiently low. Canna Coco is an example when there’s no need to flush or buffer. And other brands take care of flushing and some buffer, for example, Cloud Coir and Royal Gold Coco Fiber (note: I haven’t sent them for lab testing).
I like (and use without flushing) Cloud Coir (50/50 coco/perlite) for two reasons; although I prefer a 60/40 or 70/30 coco/aeration amendment mix:
- Oxygen is the #1 overlooked and underappreciated factor in soilless media and soil cannabis cultivation. Coconut coir has low air porosity and high container capacity, remediated by adding perlite (zeolite, PBH, etc.). Increasing coco coir AP closer to 20% (max 30%) while reducing CC to 60-65% (min 55-60%) significantly increases cannabis yield and growth, born out in the findings from an excellent thesis paper.
- Aeration amendment act as diluents, decreasing the relative Na and Cl within the mixed substrate compared to using 100% coco coir.
I highly recommend sending a media sample out of the bag for a saturated media extract nutrient analysis. That way, you can hopefully save yourself a lot of time and effort. I also suggest getting a porometer analysis of your substrate, so you know its AP, CC, total porosity (TP), and bulk density (BD).
Another benefit of not flushing (saturating) and draining your media before filling your containers is that you will achieve higher container air porosity; because the likelihood that your media is drained to CC near the bottom of the mixing vessel is low. A trick to increase the drainage near the bottom by reducing the perched water table is to insert some drain sticks in the base of your container, so they extend far into your media. The drain sticks allow the media capillary action to drain water against gravity. So a larger total volume of your media will achieve container capacity by reducing the percent of saturated media.
Some values from recent Canna Coco tests (SME and porometer):
- EC = 0.11 ms/cm
- pH = 5.81
- NO3 ppm = 0.69
- K ppm = 22.52
- Ca ppm = 1.58
- Mg ppm = 0.53
- S ppm = 1.29
- Fe ppm (as Fe(II) I assume) = 0.40
- Na ppm = 9.13
- Cl ppm = 27.96
- AP = 6.47% (with typical soilless media depth of 9-12" that AP is closer to 12%)
- CC = 70% (with typical soilless media depth of 9-12" that CC is closer to 65%)
- TP = 78.8%
- BD (lb/cubic ft)= 5.32
Note:
Below 10% AP is considered anaerobic - however, the porometer test uses 3" core, so the perched water table (PWT) is exceptionally high. When the PWT is high, it reduces AP and increases CC. I typically have the lab stack 3 or 4 cores to better represent cannabis container height to account for the lower PWT. Also note that as roots grow the AP tends to decrease.
Agreed; that’s why I always recommend to pre-moisten with a non-ionic surfactant even if they don’t use to include a NIS in their irrigation solution. That goes for media with NIS pre-mixed in, like peat moss media. Because the NIS degrades over time, and who knows the age and storage conditions of bags and bales of ProMix.
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I would hope so, but if I were a betting man, I wouldn’t wager on it. Given how things typically go with combustion temperatures, I assume we would find unforeseen toxins.
A more significant concern would be the possible concentration of Tween 20 (or other surfactants) during the extraction process. For example, some processors grind their biomass before ethanol extraction, likely causing Tween 20 to be extracted into the EtOH (especially if it’s not a -40’C process). And considering Tween 20 BP is 695.8°C, the downstream winterization, solvent removal, decarboxylation, and distillation are unlikely to remove it. Instead, they would probably concentrate it further. LLE could possibly remove Tween 20, but considering it’s oil soluble, maybe not (or with difficulty). Hitting a vape pen or dabbing (often very high temp) with surfactant-contaminated distillate seems unwise.
For these reasons, APG could be a better choice considering its chemical nature. I suspect it’s less likely to produce toxins at a high temperature. But I presume you would have more insight than me because you’re a much better chemist.
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Fully agree about oxygen in coco being overlooked. I am also a big fan of perlite amended coco.
Another potential amendment to increase air porosity for coco coir is rice hulls. These also don’t produce any dust, which can be a pain when dealing with perlite at large scales.
One of my favorite media to use for growing - which I am getting US growers to try - is to use mixes of rice hulls and sand. At 50/50 rice hulls and masonry sand you can obtain a very nice mixture which is much more chemically inert than coco and easier to reuse (almost no CEC). You can change the ratio of rice hulls to sand to adjust your water retention and air porosity to exactly where you want it. Plus rice hulls do provide some natural release of Si through time.
I wrote a full blog post about it if you’re interested:
If you use this media you will need to use cloth pots, otherwise your drains will all get clogged with sand 
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Beat ya to it! 
PBH in my post above = parboiled rice hulls. I used PBH with coco and peat a few years back.
I read that blog post a while ago. Have you sent it in for pore space analysis? I’ll try it in a month or so and let you know what I think.
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Does anyone know if Athena has a shelf life ? I have at least a few lbs each of core, grow and bloom that are close to two years old now. Is there a way to tell if its expired ?
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Yes is it rock hard from moisture
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What is the difference between surfactants and wetting agents, like thermx 70 for example
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In practice surfactant and wetting agent are the same thing, substances that reduce the surface tension of a liquid and therefore improve the wetting of that liquid on surfaces.
Surfactant is used more commonly when you’re talking about the substance’s ability to help solubilize substances that wouldn’t commonly solubilize, for example how soap helps dissolve fats into water. Wetting agent is used when you’re referring to the surface tension effects. At least this is my impression.
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I haven’t sent the media for pore analysis. I look forward to your results if you do send it.
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As @danielfp wrote, they are the same thing for all practical purposes. However, “surfactant” is the proper term. “Wetting agent” is (I believe) a horticultural industry term to better describe its function (maybe for marketing?). The etymology of “surfactant” is “surface-active agent.” They ‘work’ by reducing the surface tension of the substance into which they’re dissolved.
For example, surfactants and wetting agents are ‘active’ at the ‘surface,’ so, for a solution like a foliar spray, it’s the leaf-air-water interface (imporving leaf wetting). And for media, it’s the soil-water-air inference (at the media surfaces and in air-filled and water-filled pores). When referring to media, surfactants are adsorbed onto the surfaces of particles, which dissolve into water upon irrigation. When referring to an emulsion, they are ‘active’ at the ‘surface,’ i.e., the ‘interface’ of the continuous and dispersed phases.
How do surfactants affect soil properties?
Conclusions
Surfactants through alterations in contact angle and surface tension affect the physics of water retention and flow in soil systems.
ThermX 70 is a natural surfactant, where steroidal saponins from Yucca are the surfactant molecules. In contrast, the ones under discussion are synthetic and non-steroidal (except in the case of APG, which is a ‘green’ sugar-based surfactant). I wouldn’t recommend using ThermX 70 for a few reasons, including possible inhibition of beneficial yeasts and fungi for growers use arbuscular mycorrhizal fungi, Trichoderma, or living soils. The inhibition comes from the nature of the saponins because they have a steroid-like effect.
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What are your thoughts on quilaja extract powder, made from the quilaja saponaria tree, and how it be used in horticulture? How do those saponins compare to the ones in ThermX70? The product that comes to my mind when talking about saponins and wetting agents is the JayPlantspeaker QEP. I have never used this powder, but very curious about the benefits of saponins.
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Hello @Ralf. Would you suggest using Yucca? I have a huge container of it I bought to use as a surfactant for my foliar sprays but haven’t even opened it yet. Can I add it to my nutrient solution and at what rate? I think I remember you saying a few posts above about organic surfactants causing bio film in nutrient solutions after a few days. I change my nutes out every 3 days because the added fulvic causes a film after that. What would your suggestions be on the use of Yucca as a surfactant for DTW coco 70/30?
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Spot on. 70/30 coco/perlite is excellent, although recycling it as mulch is unsightly and dries too quickly.
I also did trials with Riceland after Cannabis Conference 2021 as part of our sustainability values. I didn’t have sand runoff and the trials for yield were on par with 30% perlite by volume. Freight ended up cheaper by the time the PBH were expanded compared to perlite.
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What @anon56994712 wrote, moisture absorption is your enemy. With salts, I always tightly tape the bags closed after each time I open them. I keep my one open bag per salt in air-tight containers with minimal head space. And I maintain an RH of 30-40% in the chemical storage room.
Some growers will empty each salt into an air-tight container. That can work OK if you securely place a trash bag on top of the salt to reduce headspace over the salt. It also helps to place large desiccant packs in the container, but keeping the RH as low as feasible is more critical.
Liquid or powder Type 2 (65-90% saponin content on DWB) Quillaia extract from the Quilaja s. tree is an excellent source of saponins. They aren’t steroid-like as found in Yucca. Tea saponins are also top-notch but far less common. While I haven’t looked for research on applying natural saponins from Quilaja tree bark or tea plants for root drench and foliar spray, I don’t think they’re a great choice.
Overall, at this point, I wouldn’t suggest using saponins as a surfactant for root drench or foliar spray in most cases. While saponins are an effective surfactant, their sources, like quillaia powder, are not pure enough. Hence, they’re residue-heavy and quite sticky. Quillaia extract saponins (and tea saponins) are excellent as a part of a natural surfactant system for O/W nanoemulsification. Still, I don’t think they’re great choices for drench or foliar sprays.
No, I wouldn’t suggest Yucca extract. See this post regarding ThermX 70. If you want to use saponins, I would recommend Type 2 Quillaia extract (liquid or powder) instead of Yucca extract. But again, as above, I wouldn’t recommend saponins for this use.
However, I haven’t looked at research on this topic, so I could be mistaken. You could spend some time looking for relevant research on Google Scholar, Scopus, Web of Science via. Publons, and specific journals like Frontiers in Plant Science, Trends in Plant Science, Journal of Plant Research, Plant Cell, and Plant, Cell and Environment, etc.
Good point about the quick dry back with coco mixed with aeration amendments 
; I should have mentioned it’s best paired with automated irrigation.
Did you test @danielfp’s masonary sand and rice hull mix?
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I used 70/30 coco/rice hulls in automated drip and ebb/flow. Sand is intriguing, but I worry about how much more labor would be spent moving/mixing it.
After use, the coco/PBH composts well and it is done when it compacts. It makes a medium brown mulch that holds water well and pets love to lay in it.
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I have similar concerns with sand and its shipping costs too. Plus, at scale, mixing media in-house is a significant hassle and mess, even with a large PACK Manufacturing screw mixier, water wand, conveyer belt, and potter. Some companies will do custom mixes with nearly any substrate and amendment. I’d rather pay more for a premixed substrate than mix it in-house.
I’m switching to 100% Rockwool for our new facility for all those reasons (shipping cost, mess, storage space, etc.) and improved irrigation control for dry backs, EC and pH control, and inert media.
LOL, “pets love to lay in it” - I now like you even more than I did.
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How long does it take for Rockwood to decompose?
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I’m not planning to compost at first. Instead, I plan to use the rockwool as a diluent for a 49:51 v/v ratio of cannabis plant waste to diluent when destroying the cannabis waste (shredding and mixing). A garbage truck will transport the mixture from our dumpsters to the landfill.
Once we have a few harvests under our belt, I plan to focus on composting the rockwool and cannabis waste. Hopefully, I can find a composting company to work with us.
While I haven’t extensity researched this topic (yet), I do have a background in composting science and experience composting. Rockwool (stonewool) isn’t compostable per se. But, from a minimal search attempt, using typical commercial thermophilic green waste composting (static piles) at a 10:1 v/v ratio (green waste:rockwool) can take 8-10 weeks (including a 4-week cure).
However, I assume by optimizing the C:N ratio, humic acid input, phosphorous concentration, adding zeolite powder, and using CMC (controlled microbial composting), i.e., the Luebke method, which includes turning the pile often with a compost turner, a finished pile could take 4-6 weeks for much higher quality, humus-rich compost. Using the forced aeration (air injection) method is another option to speed up the process and provide a better end product.
IMO, regardless of using rockwool, CMC provides the best quality compost one could hope for when optimized with the above inputs.
https://www.tandfonline.com/doi/abs/10.1080/1065657X.2018.1463878
Conclusion
Addition of spent rockwool to greenwaste feedstock (10% v/v) and composting it did not have any negative effect on plant growth of the three crops investigated in this study. However, dry shoot weights of okra, tomato, and chili peppers were increased with the addition of greenwaste composts both with and without Grodan rockwool at higher application rates and this effect was more prominent in plants grown in sandy soils compared to that of clay soils. Our results suggest that spent rockwool can be safely mixed with greenwaste feedstock at low volumes and can be composted without any harmful effects on plants. Further research is needed to examine the effect of composting rockwool with other feedstock materials at varying proportions including additional field trials with agricultural crops.
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I just realized you asked about time to decompose, not compost. By itself, rockwool takes a long time to decompose, if ever.
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