About Potassium Silicate

Potassium is considered by most to be the number one deficient nutrient in Aquaponics Systems. The primary reason for this is that potassium does not naturally occur in our water supply. For this simple reason, in order to have viable plants we must supplement potassium. There are a few forms of potassium that can safely be used in Aquaponics. Our favorite by far is Potassium Silicate.

Potassium silicate offers a second nutrient to plants that many growers do not realize their plants need. Silicate as of right now is not considered an essential nutrient in plants' but we feel that it is just a matter of time until it is. Silica is the second most abundant element on the planet, however very little of it is in a soluble form that is available to plants. Potassium Silicate has both soluble potassium as well as soluble silica.

What does this combination do for your Aquaponics System?

  • Corrects potassium deficiencies in our plants.
  • Supplies the correct amount of silicate to our plants when administered correctly.
  • Can be used as a safe form of PH up.

What are the symptoms of Potassium Deficiency?

  • ·         Symptoms show up on the older growth first.
  • ·         Cupping or Puckering of the leaves.
  • ·         Slight marginal chlorosis.
  • ·         Leaf margins dying, especially at the tip in severe cases.
  • ·         Abnormal fruit development.
  • ·         The flavors of fruit may also be lacking.

Pepper Plant
Split Tomato

What are the symptoms of Silica Deficiency?

  • ·         Biotic and abiotic stress.
  •           Stems and stalks of plants may be weaker than normal.
  • ·         Abnormal flower development in fruiting plants may occur.
  • ·         Susceptible to bacterial and fungal attack.
  • ·         Unable to heal from pest attack.
  • ·         Unable to fight off pest.

Abnormal Flower
Abnormal Flower
With and Without Silica

What do these elements do for your plants?

Potassium helps the plants cell walls to become more elastic as well as to help the plant move water and other elements such as iron throughout the plant.

If you have ever seen a tomato split open on the vine/bush that was in most cases caused by a potassium deficiency. The wall of the tomato do not stretch quick enough as the tomato grows, and so the skin splits open.

Tomatoes that ripen unevenly are also showing signs of a potassium deficiency.

Do not confuse blossom end rot with a potassium deficiency, that is caused by a calcium deficiency, also very easy to correct.

Silica, although still not considered essential, makes such a difference in plants that it is hard to believe it is true. You must see it for yourself to fully understand the wonderful difference it makes in plants.

When either added to the system water as a PH up or sprayed on the plants as a foliar spray (our preferred method), the silica acts as a bad bug shield.

If that is not enough, the plants will uptake the silica when they need it the most, such as during a bug attack. This allows the plant to quickly repair the damage as well as making the plant not tasty to the bugs.

Silica will not harm nor will it make your good bugs leave, however, we see fewer good bugs because the bad bugs are no longer in our garden.

Bees are not affected in the slightest as they are not here to find bad bugs, they are looking for pollen and water in our system. So you don't have to worry about them, they will still love you.

When plants have silica available to them, they can stand much more stress cause by the extremes of hot and cold as well as damaged in any form. This means you harvest more crops in the end, providing more food for your family or good crops for sale at the market. Those of you growing commercially know that one failed crop could be the demise of your business, so the simple addition of a nutrient supplement such as Potassium Silicate by default should be a priority.

Where to find the correct Potassium Silicate

Not only is watercress very easy to grow in aquaponics it is also very healthy for us. It has more vitamin C than oranges, more calcium than dairy milk, more iron than spinach and is full of minerals. 

Watercress can help to prevent cancer, boost immunity and provide support for your thyroid. Did I mention it taste great?

Side note, I have stopped writing this twice to go pick some fresh and eat it.

You can cook this stuff, add it to a salad, mix it with a drink, put it in a stew, there is no wrong way to eat it, and to be frank, I love it picked fresh.
Have to be honest, you have to keep it under control in the aquaponics system, as it is invasive. Easy to do, just pull out the plant where it is over growing and it will have to start over. And you want to do that from time to time any way to insure that the roots do not clog any parts of the system. Again it is easy to do. Just pull them up from time to time and plant them in a new location in media beds, and in DWC beds, just trim the roots when they over grow. If you do as we here at True Aquaponics suggest and keep red wigglers in your media beds, they will also be quite healthy eating the left over roots fro the old plants.

Iron Deficiencies

Iron deficiency is pretty easy to spot in most cases as it shows up on most all of the new growth of your plants. The tomato plant below is in an aquaponic system and shows a severe lack of iron. The strawberries also show a lack of iron.

Click image to enlarge!
Click image to enlarge!
The yellowing is between the veins of mostly new growth of most plants. If old growth is affected as well, look for other possible deficiencies.

Quick Guide To Iron Deficiencies

  • Young growth most affected.
  • Yellowing between the leaf veins.

Correcting Your Iron Deficiency

We use two types of "Iron Chelate" to treat iron deficiencies, and use a weekly regiment to maintain iron levels in our system water. The available soluble iron in the system water depends greatly on the PH of your system. Before you order and dose your system, make sure you know your PH and know where it stays most of the time.
  • PH at 7.5 and below, you will use FeDTPA iron chelate.
  • PH above 7.5 you need to use FeEDDHA iron chelate.
FeDTPA is available to plants from around a PH of 6.0 to 7.5 and then drops off quickly above that.
FeEDDHA is available in a PH range from the high 5's to the mid 9's on the PH scale.


Magnesium Deficiencies

Magnesium deficiency starts on older leaves. They show interveinal chlorosis on the leaf margins and some whitish to light brown necrotic dots. If deficiency is severe, interveinal chlorosis progresses from the margins to the middle of the leaflets. The small veins also become chlorotic, but the bigger veins remain dark green first. Subsequently the whole leaves are yellowing and finally the older leaves die. In this case growth is severely impaired and fruit yield is reduced.
Click image to enlarge!
Click image to enlarge!
Magnesium deficiency is one of the ones that can look like some of the others and therefore can be harder to diagnose. It can look like phosphorus deficiency but there will be no purpling of the leaves. Some of the brown spots could be mistaken for a calcium deficiency, but without BER.
Click image to enlarge!
Click image to enlarge!

Quick Guide to Magnesium Deficiencies

  • Old growth mostly affected.
  • Yellowing primarily between the veins of the leaf.
  • Older leaves turn yellow at the edges, leaving a green arrowhead shape in the center.
  • Dead fringes at leaf edges or brown spots on the leaves.
  • Most affected leaves will start to fall off.

Correcting Your Magnesium Deficiency

For all PH levels we treat in one of two ways.
  •  Magnesium sulfate is our choice for treatment, however if you have low PH and are adding the calcium carbonate that we carry, it also has magnesium in it.
  • We add to solution at times, directly into the fish tank.
  • When we need really quick results or are looking to boost fruit production on certain plants we will mix up a foliar spray for the plants.



Phosphorus deficiency is most often manifested as purple coloring of the leaves, particularly the leaf veins. In severe cases the whole plant may take on a purple hue.

Click to enlarge picture!
Click to enlarge picture!
One of the quickest and easiest ways to spot a phosphorous deficiency is by the purple color that will often show up in the plant leaves. Then you will have leaves that will have dead brown spots on the leaves that will sometimes look as though the leaves have been squashed.
Click to enlarge picture!
Click to enlarge picture!
You will also note that plants that are stricken with this deficiency will tend to be spindly with sparse growth although reaching near normal height. In some cases the leaves will  will appear dark green to bluish green. The purple color is normally found on the bottom side of older growth leaves. Sometimes tomatoes that are grown at too low of a temperature will show the sames signs, so yet another reason to keep your water and air temps at a tolerable level.

Quick Guide to Phosphorous Deficiencies

  • Look for a purple color underside the leaves of your plants. Poor fruit production can also be a tell tell sign of a phosphorous deficiency.
  • Watch for spindly growth that is about the correct height, not to be confused with a magnesium deficiency.

Correcting Your Phosphorous Deficiency

For all PH Levels we treat one of two ways.
  • Super Triple Phosphate (Chlorine Free) Hard to find but we do carry it.
  • Rock Phosphate-becoming more rare.

Be advised, phosphorous in your water can cause an algae bloom if sunlight is allowed to get to the water, through the sides or tops of fish tanks or grow beds.


Calcium-deficient plants are stunted, having distorted, cupped leaves and characteristic interveinal chlorosis. Symptoms appear first on new growth. On fruiting plants such as tomatoes and squash, blossom end rot will occur.

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Above-Leaves with calcium deficiency
Click to enlarge picture!
Above-Blossom End Rot (BER)
The easiest to detect calcium deficiency symptom is BER. First a darkened spot appears on the end of the fruit furthest away from the stem. It will grow larger and that part of the fruit will likely become sunken into the the fruit. The color could be grey or brown as well as shades in between.
Click to enlarge picture!
Click to enlarge picture!
Do not confuse this with a potassium deficiency.

Quick Guide to Calcium Deficiencies

  • Look for dead brown spots on the fast growing stems of the young parts of the plant or on the leaves.
  • Look for grey to brown spots on the fruit especially on the blossom end of the fruit. BER

Correcting Your Calcium Deficiency

For PH from 7.0 and up!
  • Calcium Chloride applied in a spray form on plants only.
For PH that is below 7.0 and dropping or drifting down!
  • Calcium Carbonate (our first choice)
  • Hydrated lime

Please note, that if you have dosed too much potassium in your system, your plants may show signs of a calcium deficiency, if this is the case, stop adding potassium and use calcium chloride to get some calcium to your plants quickly. Most water has plenty of calcium in it when it is added to an AP system, so you may want to have your water tested and see where yours stands early on before you start dosing anything.



Potassium deficiency is characterized by a cupping or “puckering” of leaves and affects older leaves first. Leaf cupping is usually accompanied by a slight marginal chlorosis, with the leaf margins dying especially at the tip in severe cases. Leaf symptoms are accompanied by abnormal fruit development, cucumber fruit often developing a brown or spotted appearance and melons often developing abnormal flesh texture and off flavor.

Click to enlarge!
Click to enlarge!
In aquaponics, potassium is the number 1 most deficient nutrient there is. The issue is very easy and quite cheap to control to insure you have healthy plants in your system at all times. One of the first tell tell signs is that your plants will start to wilt during the heat of the day, and this does not mean high heat. We see leafy greens wilting and laying down on the media beds in only 75 F temperatures. Next you will see the older leaves become chlorotic, then necrotic, from the edges of the leaves and working back to the center of the leaves.
Click to enlarge!
Click to enlarge!
In some cases, the tomatoes when becoming ripe will display areas that remain green.

Quick Guide to Potassium Deficiency

  • Old growth is most effected
  • By yellowing between the veins.
  • Plant leaves are cupping.
  • Plants are wilting.
  • Dry or dead edges develop.
  • Check for stunted root growth.
If any or all of these symptoms are present, you could have a potassium deficiency.

Correcting Your Potassium Deficiency

  When we hear the word "Basil" we normally think of pesto being made in the local Italian restaurant. I want to introduce you to the bigger side of basil, the medicinal side!!!! For those of us with gastrointestinal issues that cause gas, basil can provide almost immediate relief. It also can quickly provide relief from stomach cramps and nausea, and after super bowl 2015, some of us need that.
  On top of that, basil has powerful anti-inflammatory properties and can help with issues such as inflamed bowel conditions. Among them are colitis, IBS, crohn's and celiac disease.
    With those wonderful properties, what else does basil have to contribute to us?
  It has antibacterial and antiviral properties making it quite effective against bacterial infections, intestinal parasites, colds, flu, shingles, herpes and the flu that o many are concerned about. Full of magnesium that most of us keep our systems rich in by adding magnesium sulfate found in the True Aquaponics Store.
  Magnesium helps to relax blood vessels and muscles and supports cardiovascular health by lowering the risk of irregular heart rhythms and spasms.
  You can pick the fresh leaves and crush them in coconut oil and apply this to your skin and apply fresh daily with a bandage to allow it's fungicidal properties to aid in healing wounds, skin rashes, warts, and insect bites. You can purchase creams and salves, but why would we do that when we can grow it organic in our aquaponics systems. We add fresh basil to many of the dishes that we cook so that we get all the benefits that basil has to offer, and again, we know it is pesticide free and grown organically in our aquaponics system and can be picked daily.
  One thing to consider as the plants age and get a little bitter, use these to make your compounds for treating your skin and pick the younger plants for your meals.
On October 2 2014, Sam received in the mail a package from True Aquaponics. In this package was DTPA Iron Chelate and Potassium Sulfate, that is tried and true here at True Aquaponics. The picture of the strawberry plant above, was sent to us by Sam showing us the issues that his plants were having, and we saw that for sure the AP system was iron deficient. He also described other issues that led us to believe that he was having a potassium deficiency at the same time, which is not unusual.
Above is the second shot of the little strawberry plant that could, after it was doctored. Notice how the yellow has substantially been reduced and the leaves are turning more green?  The first picture was shot on 10/6/14 and the second on 10/8/14, I know, I would not believe it either if I did not see the pics. Next is a pic shot on 9/28/14 of another larger strawberry plant.
The pic below is of the same plant on 10/6/14, the change is not as drastic, but it is noticeable. This is what we look for to know we are doing things right when it comes to adding our supplements.

An Update From Sam

Two weeks since I started adding the Iron Chelate and Potassium to my System That I got from True Aquaponics. This is the same small strawberry plant. Looks greener today. Love the Help I have gotten from everyone at the True Aquaponics Facebook Group. You can also see an improvement in the growth as well.
And this is the Larger one. You can see the improvement on this one as well. After only 2 weeks amazing what a little True Aquaponic Supplement can do when your system has been depleted. 

Where do you find the supplements your system needs? Check the link below.

These days there are two things we really don't want to think about when it comes to spending money. How much gas it takes to run our cars and how  much power we will use in the house. However it is a big concern for many people when it comes to aquaponics, because many times pumps are running 24/7/365. I want to take this opportunity to try to help everyone understand just how much energy they will spend running their systems so that they can decide if the investment is worth it or not. Most systems will employ a water and an air pump to circulate water and provide oxygen to the fish and  plant roots. 
In our test system, our water pump uses 68 watts of power.
Also in our test system, our air pump using 18 watts of power.
Our water pump uses 68 watts and our air pump uses 20 watts, sounds like a lot of watts all the time right? In reality this system will cost us less than $7.50 per month to run. If we can't pull $8 worth of fresh organic pesticide free produce from our systems per month, we are growing the wrong things. Over the summer alone, from 5 okra plants, we pulled more than $12 per week of fresh okra, had we been selling instead of eating, there would have been profit there not counting labor or cost of the system for building it.

The okra on the grill was picked in three days from five plants in the True Aquaponics system, then grilled to tasty perfection and completely eaten by us and our dogs. They love the stems that are left over.
The point is, it does not take much produce to make up the cost of the pumps for a system in the greenhouse. During the same time we pulled many jalapenos, cucumbers, tomatoes, squash and several types of lettuce from the same system as well as herbs for cooking.
If you are looking to sell your produce, then you will need to study up on what the market in your area wants. What is it short of and what gets the best price, when these two conditions are met, then you have a winner.
Want to figure your own systems running cost? It is very simple to do. First, find out what your electric company charges you per KWH. Once you know that, then you can follow this link and use the calculator to figure your cost. Click here to open the calculator.
When the calculator opens in a new page, put in the watt usage of your pumps and lights if you use them. Then type in the time in hours and click on "Calculate". This will tell you how many kwh you are using for a given time.