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I am doing a hydroponic experiment at school comparing different fertilizers and there formulas. For this question I am comparing miracle Gro, jacks's and CN517. Miracle Gro and Jack's are both water soluble fertilizers. CN517 is a liquid hydroponic fertilizer.

I went in to check on everything and I noticed the coloring on the roots of the lettuce. The hydroponic lettuce has nice white roots. The water-soluble has a light brown color, it is noticeable.

I know this can't be from lack of oxygen. I have a air-pump pushing air through a air stone in each section, but I think this is a lack of some nutrient. After all the water-soluble was never meant for hydroponics, but this is a experiment so were looking at what happens.

Update 1: I am going to add a list of everything Miracle Gro, Jack's, and CN517 have listed on the package. But I do think CN517 is not listed EVERYTHING in the fertilizer, just keep in mind...

Miracle Gro

NPK: 24-8-16

Boron: .02%

Copper: .07%

Iron: .15%

Manganese: .05%

Molybdenum: -

Zinc:.06%

Jack's

NPK: 20-20-20

Boron: .02%

Copper: .01%

Iron: .2%

Manganese: .05%

Molybdenum: .01%

Zinc: .05%

CN517

NPK: 3-1-2

Calcium: 3%

Magnesium: 5%

Ljk2000
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  • Where's the pictures of the roots? – Graham Chiu May 04 '18 at 01:40
  • @GrahamChiu I will get something uploaded when I get the chance, it may be a while since this is at school and I would only be able to when I have the chance. – Ljk2000 May 04 '18 at 01:52
  • What’s the question? – Stephie May 04 '18 at 08:58
  • Check the trace element content of all three and compare, as well as the NPK - I can't find anything called CN517 on line to check for myself. There will be differences in the formulations which might account for discoloured roots. Jack's, though does say its not intended for use in hydroponics, its intended for use on soil based plants, see here http://www.greenhousemegastore.com/product/jack-foots-fertilizer-20-20-20/water-soluble-fertilizers – Bamboo May 04 '18 at 10:43
  • @Bamboo I can list off the trace elements contained in Miracle Gro and Jack's. But CN517 does not list everything it has I feel. I can't find it online either but the school gets it someplace... I wish I knew more on the product myself. Granted Miracle gro and Jack's is not meant for hydroponics we are comparing anyway as a experiment, I would never use the two otherwise. – Ljk2000 May 04 '18 at 12:56
  • Yea, you'd need to compare all three, particularly the CN517 - the school should know the details of CN517 though – Bamboo May 04 '18 at 13:00
  • @Bamboo I just added a list of the three comparing everything in them. I will see if the school has more information on CN517 but I wouldn't get hopes up. – Ljk2000 May 04 '18 at 13:02
  • @Stephie I guess another way to re-word it is what is the water-soluble fertilizers missing in terms of minerals and stuff that is causing the roots to turn brown, or be unhealthy. – Ljk2000 May 04 '18 at 13:11
  • Its not necesarily that the water-soluble fertilizers are missing something, my guess is that they are changing the PH of the solution [here](http://www.foodrising.org/Media/Soil-pH-Nutrient-Availability.jpg) you can find a nutrient availability chart. Can you check the PH of the 3 solutions? If PH is off, nutrients are unavailable for the plants. – Petar Petrov May 04 '18 at 14:29
  • @PetarPetrov Thanks for bringing that up since I never thought of that. My school has a expensive digital Ph meter, I will check that as soon as I can, will let you all know what I get. – Ljk2000 May 04 '18 at 15:39
  • @PetarPetrov The results are in and I am happy I checked! I found water-soluble to be 7.9Ph and CN517 to be 7.4Ph, thank you again fro bringing that up. – Ljk2000 May 04 '18 at 16:30
  • Also, I forgot to mention about [salinity](http://www.plantstress.com/Articles/salinity_i/salinity_i.htm) which is more likely to burn the roots, you can use a TDS meter or an EC meter. Non hydroponic fertilizers tend to increase the salinity. (But it really depend on brands and product) – Petar Petrov May 04 '18 at 17:27

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