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what TDS level for leafy greens and herbs in indoor Tower Garden?


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  #1  
Old 10-18-2017, 11:40 AM
twd000 twd000 is offline
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Default what TDS level for leafy greens and herbs in indoor Tower Garden?

I picked up a Tower Garden second-hand and set it up in my dining room over the winter. Growing leafy greens and herbs (romaine and bibb lettuce, spinach, broccoli raab, kale, swiss chard, parsley, basil, cilantro, etc.). No fruiting or flowering plants. T5 lights on 14-hour timer. nutrient pump on 15 minutes, off 45 minutes cycle. The "Tower Tonic" that came with it is 5 years old...I mixed some up it got very low TDS readings so I'm not going to use that. I have some General Hydroponics Maxigro that I will use instead.

My question is what is a good TDS level to target for this system? The Tower instructions recommend 1100 for half-strength solution (summer time) or 2200 for full-strength, which seems REALLY high to me. But it's also a one-size-fits-all for people who may be growing lots of tomatoes in their Tower outdoors.

So what TDS level should I try to maintain, assuming I have a mix of greens and herbs at various growth stages at all times?

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Old 10-20-2017, 11:41 PM
GpsFrontier GpsFrontier is offline
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Hello twd000,
Maxi grow has mixing directions right on the package. I believe it's 2 tsp per gallon of water for full strength nutrient solution. Don't get caught up trying to fallow TDS numbers. Not only are you trying to grow many different plants in the same system making any TDS values worthless. But any TDS chart is only a general starting point. There are so many environmental variables that change nutrient needs, not to mention size and age of the plant that TDS/PPM and EC charts are really only good for determining if the plants are heavy or light feeders in comparison to other plants. If your looking for a TDS/PPM/EC charts, here you go.

TDS/PPM/EC Requirements for Vegetable
TDS/PPM/EC Requirements for Herbs

P.S.
Broccoli rabb is a flowering plant, the broccoli heads are the flowers.

Many of the plants you mentioned are light feeders, but others like Kale, Broccoli and spinach are heavier feeders. A general rule of thumb, the darker green the foliage is the heavier feeder it is. Mixing the nutrients to about 80% of full strength for mature plants is generally a good starting point. Just watching your plants grow and knowing what to look for will tell you if the plants nutrients are depleted as well as too strong or week.
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Last edited by GpsFrontier; 10-20-2017 at 11:45 PM.
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  #3  
Old 10-23-2017, 10:50 AM
twd000 twd000 is offline
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thanks for the reply.

The Maxigro label calls for 1-2 tsp/ gallon. I just mixed a test batch:
1 tsp/gallon = 1100 PPM
2 tsp/gallon = 2200 PPM
Would you recommend 2200 * 0.80 = 1760 PPM?

What are the signs of over- or under-fertilizing? I would expect yellowing leaves if under-fertilized...what about too much? Curling leaves?

How do I know I'm near the maximum growth potential? Will stronger solution cause faster growth?

Can I infer anything from the change in nutrient level in my reservoir over time? I assume young plants will be slow to take up nutrients. Not a lot of evaporation indoors.
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Old 10-24-2017, 12:06 AM
GpsFrontier GpsFrontier is offline
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Hello twd000,
The larger amount (2 tsp) is full strength for maxigro. As long as you know the manufactures recommendation for full strength nutrients you can adjust the nutrient strength to whatever parentage you want by simply adding or reducing the amount of water. If you mixed 4 gallons of full strength nutrients, and added a gallon of plain water you would have 5 gallons of 80% strength nutrients.

Don't get hung up on TDS/PPM/EC meters and values. Their a nice novelty to have around if you have money to burn, but don't really do anything worthwhile. In all the years I have been growing hydroponically I have never used one. Not only can they give you false readings, but cant do the only thing I want them to do.

Quote:
Would you recommend 2200 * 0.80 = 1760 PPM?
How strong I mix the nutrients would depend on many factors. Everything from the size of the plants, to the temperature and humidity, the type of plants, and probably even the size of the reservoir. Many more environmental factors will affect nutrient uptake even the amount of light and Co2 levels.

If I'm not familiar with a particular type of plant, that's when I may look at a TDS/PPM/EC chart. Not to try and mix my nutrients to the exact value on the chart, but to compare that value to other plants. That way you can determine if it's a heavy or light feeder, or somewhere between.

As an example: if I wanted to grow a plant and diden't already know I could look at the Vegetable Requirements chart to compare. You can see the recommendation for Lettuce is 560-840. when compared to all the other plants you can see the average on the high end is around 2100 to 2800 with some going as high as 3500. And the average on the low end is around 580 to 980.

Now if I wanted to grow Broccoli, with a recommendation of 1960-2450 PPM I can see it's on the high end, but not as heavy a feeder as some others. Remember temperature, humidity, size of the plant will all be considerations, but I would mix the nutrients closer to the full strength range. Probably in the 80-100% range. I would say unless the weather is hot, but broccoli is a cool weather plant and wouldn't do well in warm temperatures. Now if I wanted to grow Lettuce and a recommended PPM value is 560-840, I would probably only mix my nutrients to around 50%-60% strength because it's a very low feeder.

If I wanted to grow peppers I could tell from the chart their on the high end and a heavy feeder. I could also tell from the chart that sweet peppers aren't as heavy of a feeder than the hot peppers. Sweet peppers I would probably mix around 80%-90%. Regular peppers I would make a little stronger liken 80% -100%. If I were growing hot peppers I would probably mix around 90% to 110%.

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What are the signs of over- or under-fertilizing? I would expect yellowing leaves if under-fertilized...what about too much? Curling leaves?
Yes if you look at your plants daily and notice the new leaves coming out are a little yellow, assuming your pH is in range, then your nutrients are depleted. Yes curling leaves are a sign of your nutrients being to strong, usually curling around the tips and edges. But you may also notice the leaves suddenly become warped/deformed. If the leaves are dark green and otherwise look healthy but curling or warping, you'll want to dilute the nutrient solution.

Quote:
How do I know I'm near the maximum growth potential?
By observing your plants daily.. As well as providing them the optimum environmental conditions to reduce stress on them. That way they can focus on being healthy and happy rather than having to try and overcome hardship that will put stress on your plants.

Quote:
Will stronger solution cause faster growth?
Only if your nutrient solution was to weak to begin with, and if it was you would see yellowing leaves. If your plants leaves are healthy looking making the nutrient strength stronger will just damage your plants.

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Can I infer anything from the change in nutrient level in my reservoir over time? I assume young plants will be slow to take up nutrients. Not a lot of evaporation indoors.
Not really, again that's why TDS/PPM and EC meters are pointless to me. Sure over time the nutrients will become depleted in the nutrient solution, that's a given, and how quickly depends on how big the plants are compared to the water volume. Again common sense, no meter needed. Now if your referring to how quickly the nutrients become depleted after a nutrient change. The bigger the plants get the quicker the nutrients will become depleted. That is unless you increase the water volume as the plants get bigger. Think of it like a human. Will a little kid eat as much as a full grown adult? No.

That's why you need to design your system to hold enough water volume for not only full size plants, but have enough water volume for the total amount of water as well. As the plants drink up the water daily the nutrient solution will become more concentrated. The more the nutrient concentration fluctuates, the more stress on the plants. You want to replace what the plants drink with plain water. I always mark the inside of my reservoirs so I know exactly how much their drinking, and how much water to replace. I'll also sometimes add some diluted nutrients back to the reservoir to prolong the nutrient change.

Lastly the one thing I want a PPM/TDS/EC meter to do, it cant. It can't tell you what is in the water, much less how much of each element there is. It can only tell you the total volume. It can't tell you if there ate unwanted elements in the water. It can't tell you if your plants are consuming more potassium/calcium.iron etc. etc. Think of it like a measuring cup, you can pour a little of this in it, a little of that etc, at the end of the day it can't tell you what's in it much less how much of each, it can only tell you the total volume. PPM/TDS/EC meters are the same way. I can easily control the nutrient strength withough't a meter. What I cant do is tell what the balance of the nutrient in that solution is, and no meter can tell you that either.

Since plants use what they need and leave the rest, that means over time the balance of nutrients will change. You can add nutrients back to raise the PPM'TDS/EC meter values back, but since plants don't use them in even ratios eventually you will wind up with some elements reaching toxic levels regardless of what the PPM/TDS/EC meter reading is. That's why you do nutrient changes, to avoid the buildup of unused elements.
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  #5  
Old 10-24-2017, 10:32 PM
twd000 twd000 is offline
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thanks for the feedback on the nutrients

I'm also looking to buy two LED strip lights to augment my two existing T5 fluorescent fixtures. Does anyone have experience with this Agromax light?
http://www.htgsupply.com/products/ag...ight-led-white

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