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A Yucca stock solution to match SM-90

berkshirebud
Prominent Member CfC Advisor
Cannabis Fan
Completed Grows

As the nutrient supplement tutorial ( https://www.cocoforcannabis.com/supplementrecs/) mentions, SM-90 is no longer available and Dr. Coco now recommends using powdered Yucca at 1/8 tsp per 5 gallons. But, what if you don't want to make that much? 1/40 tsp is pretty hard to measure accurately. While using too much doesn't hurt the plants, it can make your reservoir foam up. And using too little reduces the wetting effect. What's a poor grower to do?

The answer is to make a stock solution that matches the strength of SM-90. How do you do that? Well, the nutrient schedule suggests 2.5 ml of SM-90 per gallon or 12.5 ml per 5 gallons. So 1/8 tsp of yucca is equivalent to 12.5 ml of SM-90, and 1/2 tsp of yucca is equivalent to 50 ml of SM-90. If you prefer to use a digital scale, 1/2 tsp of yucca weighs 1.6 g. Doing some math, 16 grams of yucca to 1 liter of water will make a stock solution of Yucca wetting solution at the same strength as SM-90.

My initial recipe for this was for just 50-ml, and I was mixing it up every couple of weeks. Then I discovered how hydrophilic the RAW yucca powder is. The more times I opened the bag, the more rocks of powder I got. So, I switched to mixing it up  in larger batches, which is what I recommend.

Making a stock solution of Yucca to match SM-90

  1. Rinse an empty nutrient bottle well (at least triple rinse), remove the label, and use a permanent marker to write "Yucca wetting solution" on it. I also put a "Y" on the lid. 
  2. The General Hydroponics "1 quart" bottles have a ring near the top that is very close to 900-ml. If you are using a different size bottle, you will have to do some math.
  3. Add 900 ml of distilled or RO water to the bottle.
  4. Add 14.4 g (1/2 oz) of RAW Yucca powder and stir well. If your Yucca has gotten hard and lumpy, let it  soak overnight and then stir to finish dissolving. Do not shake to avoid foaming.
  5. Since you will likely be using this just a few ml at a time, you may want to keep some of the solution in a 10-ml ( https://amzn.to/2QCdT7r) or 60-ml ( https://amzn.to/2whzpEO) syringe. I label my syringe on the plunger end with a "Y" for Yucca.

Then, wherever SM-90 is called for, use the same amount of Yucca stock solution.

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Posted : 05/11/2020 7:29 pm DEEBOOF, rarerooster, Spacedghost and 7 people liked
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  Anonymous
Cannabis Fan
Completed Grows

Thanks Berk, this worked GREAT!!

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Posted : 10/03/2021 10:37 am rockybandit and berkshirebud liked

I'm giving Roots Organic RAIN meeting agent a spin.   Dosing at 2.5ml per gallon (as a replacement for SM-90 in standard CFC nutrient chart).  Noticing a bit more foam in my reservoir than normal.  Will try to dosing down a bit to see if that helps reduce the foam in my res.   If not, I'm going with Berk's approach.

https://www.aurorainnovations.com/rain

 

 

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Posted : 04/11/2024 9:39 am

I'm giving Roots Organic RAIN wetting agent a spin.   Dosing at 2.5ml per gallon (as a replacement for SM-90 in standard CFC nutrient chart).  Noticing a bit more foam in my reservoir than normal.  Will try to dosing down a bit to see if that helps reduce the foam in my res.   If not, I'm going with Berk's approach.

https://www.aurorainnovations.com/rain

 

 

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Posted : 04/11/2024 9:39 am
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