# Used up hydroponics water for fertilizer?



## Hayjosh (Mar 24, 2016)

Here in Michigan Cannabis has been legalized so growers and Cannabis shops have popped up like crazy all over the place. Almost all of the growing is done exclusively with hydroponics and the water needs to be completely changed out about every two weeks.

Though much of the nutrients will be used up when the water is changed out, I've been contemplating collecting the waste water from the grow shops so I can spray it on my fields, if I can get meaningful quantities. It could keep a constant source of maintenance nutrient trickling into the soil and the pH of the water is regulated.

This idea sounds especially appealing to me especially in light of current fertilizer prices. I've called some shops and they have to check into regulations to see if this is allowed.

Is there any reason this could be a bad idea for plant and soil nutrient management?


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## sea2summit (Aug 4, 2021)

Not sure there would be enough juice to be worth the squeeze. Have you tested the waste water to see what's left?


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## Hayjosh (Mar 24, 2016)

I don't even have any water yet, I'm just doing some exploratory investigation first.

Idea came about when a large grow facility that was wanting to go up near me asked the local MSU extension farm if they knew any producers in the area that would be interested in the waste water. MSU asked me, but then my township voted to change the zoning to not allow the grower to setup shop there, so it never materialized.


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## Hayjosh (Mar 24, 2016)

I just found this so sounds like it's not doable.

*Cannabis Plant Waste*
Most types of hydroponic plant waste—including waste from tomatoes, peppers, and cucumbers—can be discarded as you see fit. But if your hydroponic system is used to grow cannabis, you’ll need to follow strict protocols for waste disposal.

Every cannabis licensing agency in the U.S. has its own disposal requirements, but certain guidelines are common. For example:


Cannabis waste must be rendered unusable and unrecognizable. While there’s no uniform definition of what constitutes “unusable and unrecognizable,” the plant matter is often ground down and mixed with detergent or other toxic solutions.
Cannabis waste must be combined with at least an equal amount of non-cannabis waste.
Cannabis waste must be discarded at an approved processing facility, such as a composting site.
If you run a dispensary, cultivation facility, or other commercial operation, the rules are even more stringent. For businesses subject to state regulations, cannabis waste must be weighed and documented according to the state’s track-and-trace system. That’s why it’s critical for businesses to employ the services of a cannabis waste disposal company.


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## IH 1586 (Oct 16, 2014)

I'm with sea2summit, is it worth the diesel and time to apply it. I have similar idea only mine is with streams and irrigating. I have fairly square fields with streams near them and have been intrigued with the wheel irrigation system. Up stream I have large dairy's that over flow their pits and all the runoff from surrounding fields that the streams a green with algae. But I know nothing about irrigating and not sure if the return is there even if it does help the environment.


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## IH 1586 (Oct 16, 2014)

Hayjosh said:


> I just found this so sounds like it's not doable.
> 
> *Cannabis Plant Waste*
> Most types of hydroponic plant waste—including waste from tomatoes, peppers, and cucumbers—can be discarded as you see fit. But if your hydroponic system is used to grow cannabis, you’ll need to follow strict protocols for waste disposal.
> ...


While it does say hydroponic, it really seems more focused on the plant material itself not so much the water.


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## sea2summit (Aug 4, 2021)

IH 1586 said:


> While it does say hydroponic, it really seems more focused on the plant material itself not so much the water.


How I read it as well, think they're trying to keep the highschoolers out of the dumpsters.


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## Hayjosh (Mar 24, 2016)

If it is doable and the water isn't regulated, I'd have to test the water first to determine if it's worth it. My tractor is a fuel sipper, but with the cost of fertilizer it may be justifiable, depending on how much nutrient the water has. I think it could work well with flood tips on a sprayer.


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## slowzuki (Mar 8, 2011)

Yup need a test of the waste water to do some math. Trucking water gets expensive. We ran some numbers on trucking free mink manure from 15 miles away and free doesn't look so great against proper fertilizer to get lbs/acre targets.


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