News » 01.07.2025 - “Recirculating sounds good in theory, but the reality is much different”
"We're seeing a strong pivot in 2025 where growers want more control with less exposure to risk. Substrate choice, irrigation style, and sanitation strategy are now a core focus in every high-yield operation." HortGrow, with Product and Business Development Manager Chris Vaos, is focusing on substrate and system strategies for high-performing greenhouse facilities.
From large-scale operations to compact urban vertical farms, growers are moving away from traditional, higher-risk systems in favor of approaches that offer greater precision, improved sustainability, and simpler operations.
Aeroponics: Still a niche, despite the tech hype
Aeroponics has long been hailed for its high-tech potential, offering pinpoint control over root zone nutrition. But despite newer emitters and improved sensor tech, its reliability still falls short for large-scale commercial deployment.
"There have been advances, sure, but I wouldn't say they're making aeroponics any more reliable," Chris mentions. "Power outages, clogged nozzles, and limited nutrient flexibility still make it a tough sell unless you're doing research or growing in a highly controlled lab environment."
The decline of recirculating systems?
For years, recirculating hydroponics like ebb & flow or NFT were favored for their water-saving promise. But increasingly, growers are opting for drain-to-waste systems, primarily to reduce biofilm and root disease transmission.
"At Indoor Ag-Con earlier this year, a lot of vertical farmers told me they're moving away from recirculating," Chris shares. "Drain-to-waste is really the only way to fully prevent cross-contamination between plants. It's not just about water anymore - it's about crop security."
The problem is systemic: "If even one plant gets infected in a shared system, it'll spread quickly to the entire crop."
Bottom left is Ruck's Citrus Nursery using peat (Frostproof, FL) and bottom right Photo Credit: WGVU Public Media; Patrick Center
Hybrid systems: A trend that's fading
Though hybrid systems which features of both recirculating and drain-to-waste have gained interest, Chris doesn't see them as a viable solution to the contamination problem.
"The concern with any form of recirculation is still the same. Once a root-borne pathogen is introduced, it's nearly impossible to isolate it without dumping everything."
Media trends
Among substrates, coco coir continues to take market share from both peat and rockwool, thanks to its neutrality, sustainability, and ease of use.
"Coco coir is absolutely dominating commercial growing right now," Chris states. "Even companies known for peat-based mixes, like Promix, are offering coco-based blends to meet the demand."
As for new substrate alternatives? "I haven't seen any credible contenders to coco coir in 2025," he adds.
What about peat and rockwool conditioning?
While coco coir often comes pre-buffered and pH neutral, rockwool and peat still require the same classic conditioning methods.
"There haven't been any real advancements there," Chris says. "Rockwool still needs an acid wash to get the pH down. Peat still benefits from lime buffering or even calcium silicate, which not enough growers are using."
Drain-to-waste vs. recirculating: The water efficiency debate
Drain-to-waste systems are often criticized for using more water, but Chris challenges that assumption.
"Recirculating sounds good in theory, but when you have to dump your reservoir every 5–7 days, are you really saving water? With drain-to-waste, especially using modern monitoring tools, you can irrigate with only 2–5% runoff and keep everything dialed in."
Seen at the bottom in the photos are examples of the DWC system consumed by plant roots, and an aeroponic system with roots clogging drains
Best practices for sustainable runoff management
According to Chris, sustainable runoff management comes down to monitoring and strategic irrigation timing.
"Use real-time EC monitoring, split your irrigation into Phase 1 and Phase 2 cycles, and regularly analyze the substrate with tests like Saturated Media Extract," he recommends. "It's all about making sure plants are actually using what you're giving them, and nothing is building up."
In regulated industries like cannabis, runoff is even more critical.
"One California facility I worked with was paying $6,000 a week to truck off their runoff due to strict environmental regulations. In those cases, drain-to-waste with zero discharge is the only sustainable option."
The most common mistakes
New to greenhouse growing? Chris warns that many startups underestimate system complexity.
"Undersized pumps, no check valves, and missing inline EC or pH sensors - these are huge liabilities," he cautions. "You also see people relying on manual climate control in dynamic environments. That's a recipe for disaster."
Labor & safety are shaping substrate preferences
Increasingly, labor efficiency and worker safety are influencing what substrates growers choose. Rockwool, once a mainstay, is losing ground.
"Rockwool is basically fiberglass," he says. "You now need PPE and even respirators when handling it dry. It's pushing growers to more worker-friendly options."
The shift is also practical.
"Coco coir slabs that self-expand with water are cutting prep labor dramatically. For a grower managing multiple zones or teams, that adds up fast."
He adds that growers must choose tools that serve their specific goals, not just what's been done before.
Source: www.floraldaily.com
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