Large Scale High Pressure Aeroponic Grow - Recirculating or Drain to Waste?

Hello all, I'm building a large scale medical grow using aeroponics and I've been debating with my team whether or not we should recirculate nutrients or drain to waste.

One argument for draining to waste is as follows: The nutrient solution starts in the reservoir with a specific amount of each element (we'll call this solution A). When the nutrient solution is sprayed onto the roots, they uptake a certain amount of each element. The run-off solution, we'll call this solution B, now has different amounts of each element than solution A. Over time, as run-off solution B is recirculated back into the reservoir with solution A the amount of each element changes and we don't have a way to measure this other than monitoring EC and pH but this doesn't tell me how much of each element is in the solution... I don't know how much Nitrogen, Potassium, Phosphorus etc. has been taken up by the roots and I don't know how much is left in the run-off solution B. Over time, by continually adding solution B back to solution A the nutrient profile will gradually change from the original nutrient profile A and could cause problems with the plants.

The obvious benefit of recirculation is cost savings on both water and nutrients which are quite large doing a large-scale grow.

I've also read that when growing using aeroponics one should not recirculate during the flowering cycle even if they decide to recirculate during the veg cycle... what are they reasons why? I'm thinking it's because the plant consume far greater amounts of certain nutrients during this growth phase and recirculating the run-off creates drastic imbalances in the nutrient solution found in the reservoir.

Is this as big of an issue as I think it could be? I've heard advice saying it's not a big deal and that aeroponic grows should be recirculating and I've also heard advice saying this is a bigger deal that most growers think and I shouldn't recirculate nutrients. I haven't found any research papers on Sci-Hub discussing specific nutrient uptake during veg and flower cycles for Cannabis and the technology to monitor for specific nutrient levels in a solution is either cost prohibitive or non-existent... any one have any leads on this?

Does anyone with aeroponics experience have any advice or guidance on this particular issue? Am I correct in thinking that recirculating nutrients will lead to an unbalanced nutrient profile? Is the amount of run-off too insignificant to really make a difference?

I know I've asked many questions and I'd be grateful for any answers any of y'all might have.

I would recirculate the nutes and flush and change as desired... Easier to keep temps and all that in line with a res and chillers ect... Focus on filtration and cycle timers and you will get amazing results even changing nutes once a week...

Hey PetFlora, thanks for the reply. Large-scale in this context is a 70,000 sq. ft. sealed greenhouse with 30' sidewalls and we'll be growing 7000 plants to start, eventually scaling up to 10,000.

I've actually been reading many of your posts since you seem to be an aeroponic expert. I've also been combing through the "TAG - Landing (Resource for True Aero Growing)" thread.

Dont over think it - keep it simple and do drain to waste.

There are some studies that show that the amount of water n nutrient that use extra in a drain to waste setup is not that large as many think.

You have as u say microbes - plants that will twist n tweek the nutrient profile - plus u could end up with massive biofilms ect clocked emitters ect - pH issues -

why introduce such elements esp if you dont have much exp with growing

One tip get a nutrient pump that can inject hydrogen peroxide in the intake water n keep, the rez clean - dont use to much organic hokuspokus just stick to salts and keep the system clean, you be fine.

Keep it simpel

Thanks for the reply Dkgrower. Keeping it simple is definitely important. I'm thinking if we use a 1 second on cycle with a 5 minute off cycle the amount of run-off will be minimal. The pH imbalances and tweaking of the nutrient profile are my biggest concerns...

I'll be using an automated fertigation system and plan using one of the dosers to supply H2O2 as a sterilizing agent.

CosmicSlop said:

Hey PetFlora, thanks for the reply. Large-scale in this context is a 70,000 sq. ft. sealed greenhouse with 30' sidewalls and we'll be growing 7000 plants to start, eventually scaling up to 10,000.

I've actually been reading many of your posts since you seem to be an aeroponic expert. I've also been combing through the "TAG - Landing (Resource for True Aero Growing)" thread.

Click to expand...

Wow. Hopefully Atomizer chimes in


good luck!

CosmicSlop said:

I'll be using an automated fertigation system and plan using one of the dosers to supply H2O2 as a sterilizing agent.

Click to expand...

Seems like a dead thread, but...

The hobby HPA systems won't scale up to the size you are talking about and if you're getting ideas from forums, you're heading in the wrong direction. The pumps, controls, pretty much everything is going to be different.

https://www.tweed.com/blogs/vault-archive/116406340-r-d-sees-positive-results-in-new-aeroponics-trial

Drain to waste not, want not. Even if you recirculated for just a few days here and there that adds up to savings.. am I right?

I kinda thought the idea of HPA was to spray such a fine mixture that you only need to use low doses and so not much is wasted, leaving no need to recirculate?

Anyways.. I can imagine the perfect HPA injection grow system would utilize a hybrid combo of both DTW and recirculating capabilities, at the same time or any ratio that works at any givin' time.

The system would have an intermittent cleaning cycle, where right after the pressure holding tank and solenoids, h202 is injected and sprayed through the nozzles and into the containers. At the same time a flap would rotate to block the jet stream from hitting roots while the atomizer orifice is opened wider to self clean itself of any debris. Meanwhile another large valve is triggered and the solution is routed to the drain instead of back to the res.

The next on cycle would be the rinse cycle, kinda like a laundry machine, and then right afterwords the DTW valve would close and the system would start recirculating again.

Also at the same time as these 2 or 3 cycles happen (adding up to say 5% of the total in one day, or 2 out of 20 sprays for example..) ,fresh solution would also be introduced into the res, at the same rate as the h202 injected cleaning solution drains to waste.

Recirculating in flower means if one gets a problem (root rot) within 24 hrs they've all got it

Also as you pointed out in the OP the exact proportions of what's in the feed drifts further away from what you're adding as the grow goes on

Why would they want today what they didn't want yesterday?

OK you use more nutrients but you're a lot less likely to have a problem that slows things down and wastes your time ....its easy to recoup the cost of the additional nutes several times over with increased production

You are just starting out, but you want to do the most complex, knife edge system out there ? On a massive scale ?


Never mind any of the details, you are making a massive mistake right there with the basics. Go with tried and trusted solid methods, run some experiments alongside to learn, if not, your next posts will be bemoaning one of 1001 possible issues with a large scale Aero setup.

If large scale Aero is so easy, please point me to a few successful threads, grows, run like that.