This is my first attempt at hydroponic growing. My first group of plants are about 2 weeks old from seeds. Out of 11 most look very healthy, but 4 and in particular one have several negative symptoms. Below are pictures of the worst plant, with some plants in the background starting to show problems.

It starts as a yellowing of leaf edges and very slight upwards curling followed by full flushing of yellow and downwards curling then finally brown dead spots.

With some research I first thought it was over-watering, so I added vermiculite to the coconut fiber medium but the symptoms continued to worsen. Now I am thinking it could be a problem with nutrients or water. I used Miracle Grow 30-10-10 in a 1/2 dose and MagiCal calcium, magnesium, and iron supplement (Coconut fiber tends to lose calcium) for the initial two weeks and now I have removed the Miracle Grow. Below is the analysis of my water:

Nitrate: 40ppm
Nitrite: 0
Total Hardness (GH): 300ppm
Total Alkalinity (KH): 160ppm
pH Level: 7

I do not think this is a light issue, I am using 6 T5 vegetative fluorescent tubes 4" from leaves 21/3. Temp 28C. Unsure of humidity. Ventilation and air flow good.

All help and suggestions are greatly appreciated.

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What is the PH of your tap water, and what are you adjusting it too?
5.8 is what it should be at.

Also you need to get a good base veg forumla.
you said you removed the Miracle grow, but you need to replace it with a fertilizer.

Go to a grow shop and ask for some stuff called MAXIGROW.
use at 1/4 strength with no CAL-Mag added in PH water to 5.8

It should solve your problems.

Also It is my opinion that by the looks of your pics you are not watering enough for the coco medium.

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Thanks for the great advice.

I am going to increase the water regimen to 200ml twice a day. I don't have an active hydroponic system so perhaps I should try to water several times a day?

Also if I may ask what makes you think I am under watering, is there something visible about the plants that makes that evident?

Coco fiber requires different nutes than are in a regular hydro set up plants that small really don't need much in the way of nutes at all. Be careful with how much you water Coco fiber holds moisture pretty well so It would be best to let it dry out a little between waterings and then saturate it completely hold off on all those chemicals though! They are just babies and you are trying to feed them steak.

Coco is a hydroponic medium, it resists compaction.

So There is evidence thats says it IS IMPOSSIBLE to overwater coco.

I would completely pour water into your bags until you start getting runnoff.

And do this everyday.

Question:
What does overwatering mean, and is it possible in COCO?

Answer:
Overwatering means that a medium has so much water in it that the spaces in between the medium that normally contain air, are all filled with water. When this happens the plants roots cannot find oxygen and quickly use up all the dissolved oxygen in the water, and then cannot breath.

However in COCO, since it is so highly resistant to compaction and has a amazing abilty to drain excess water and only hold water on its inert outsides, it is almost impossible to overwater.

Many will use COCO in a flood and drain system and Flood the trays up to 3-5 times a day. Many Soil growers see this as extreme overkill, yet COCO mediumed plants LOVE IT as air is almost always viable to the plants root.


I said you underwatered because in the pictures you can see dry coco, and the spots where it was watered onto. What I do personally is completely saturate all the coco in the bags once a day until I get 15% runoff.

Having done soil grows in my past, This is a hard concept to grasp and very well feels like it cant be good for the plant, but COCO is just one of things where it defys logic.

Treat COCO like you are growing in hydroton.

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Coco is not hydroton (hydroton does not retain water) GG it has certain organic properties and is not completely inert it is not a true hydroponic grow. It is a soiless medium in order to properly feed plants you have to use nutes made for coco coir. You need to water more often because it drains water readily. It is better to fully saturate this medium to prevent shallow rooting. If there is no wilting then it is likely that the problem is not over or under watering. This seems to be more likely a nutrient problem and a ph of 7 could cause that in a soilless medium adjust your ph to be closer to 6 flush the fiber with pure water to ensure that there is no salt build up from the previous miracle grow feedings. Then feed with approved coco fiber nutes fully saturating the medium allowing it to dry a little between watering to encourage healthy root growth. Also be light with nutrient at this stage of growth your plants are still very small. good luck

Looks like it could be a nitrogen deficiency. More likely a PH problem though

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COCO specific nutes are a ripp off, COCO does not need COCO specific nutes.

all they are nutes with cal mag built in and triple the price.


Treat it like a more spongy version of hydroton.

http://www.generalhydroponics.com/ge.../faqmedia.html

second paragraph down.

WHAT IS COCO PEAT?
Answer: Coco peat is an organic medium made from coconuts, frequently used in both hydroponics and seed sowing mixes. Its advantages are that it is lightweight, relatively inert and comes from a sustainable source. However, coco peat comes in various grades, and can actually be detrimental to plant growth if it contains salt-water residues from poor processing.

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I am pretty sure that the cal mag in those nutes is because coco coir tend to leach them more quickly than other nutes. But can you use soil nutes in coco coir GG?

As for soil nutes, No i wouldnt use them because most if not all soil nute are PH buffered for soil.



there is much debate concerning Coco Specific nutes.

Ok here is a quote from stevewinthorp (he knows his shit) from homegrown.com

"
Coco nutes have a lower salt content (because coco HOLDS salt like nothing you've ever seen) and it leeches magnesium like you wouldn't believe.

I wouldn't recommend epsom salts, only because coco will pull the magnesium out and leave you with a very salty medium afterwards.
And coco nutes (specifically canna brand) don't have a lot of extra calcium, because coco doesn't leech calcium, in fact, some people have had problems with over calcifying their coco with a cal-mag supplement, which causes pH issues and some other curious symptoms.

As far as forums with good information, icmag happens to have a pretty large coco community with knowledgeable folks. Not the friendliest place, so i don't post, but I lurk there a lot.


In my own personal experience, I thought I was doing awesome in coco with my standard hydro nutes, then I bought a small canna coco set of nutes on a whim, just to try things out. Needless to say, I have never seen faster, more lush and beautiful growth, than when I started using the coco nutes... Although it's slightly more expensive, I wont use anything else in my coco grows from now on.

-- steve"



as well as a link to a thread debating coco specific nutes

Coco specific nutrients [Archive] - PlanetGanja.com

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