Nutrients and Fertilizers
What do plants need for nutrients?
According to planted tank guru Steve Hampton, the necessary nutrients are the following:
Macro Nutrients include Nitrogen, Potassium, Phosphorus, Magnesium, Sulfur, Calcium, Carbon, Oxygen, and Hydrogen.
Micro Nutrients include Iron, Manganese, Chlorine, Zinc, Boron, Nickel, Copper, and Molybdenum.
Some of these macro nutrients kind of take care of themselves, like hydrogen and oxygen. Hydrogen and Oxygen = H2O, so if you have water in the tank then that part is covered. Nitrogen is produced in an aquarium by a result of the nitrogen cycle if you have fish, but in high light tanks with a heavy need for nitrogen, sometimes they are dosed in the form of nitrates. Magnesium and Calcium ions comprise your GH , or general hardness of your water. When someone says ” I have hard water.” they mean that they have a high GH.
If a person has extremely soft water then they may need to dose magnesium and/or calcium. Some phosphorus can be found in a tank just through the fish food, but high light tanks might require more than what the fish food can provide, or a person might use fish food with low phosphorus. Some carbon can be found in the aquarium already as well, but not enough to help out the plants much. It is usually dosed in medium to high light tanks, but can be of benefit to most any planted tank. It is usually added in the form of co2 injection, or can even be added by way of a liquid such as Flourish Excel which produces carbon in the leaves of plants as part of a chemical reaction. Sulfur is usually added incidentally in the form of sulfates.
With the micro ferts, most need to be added in the way of a comprehensive trace fertilizer. Some can be found in tapwater to varying degrees. Chlorine is usually incidentally added as Chloride, which is incidentally necessary for humans to survive as well. In fact, most all of what plants need humans need as well!
Types and Brands of Fertilizer and their Applications
You can group most bought fertilizers into three categories - Commercial liquids, dry bulk fertilizers, and substrate fertilizers.
Commercial Liquids- Not all brands are created equal. My favorite brand of fertilizers is Seachem’s Flourish. They have pretty much the full line, including trace fertilizer, iron, potassium, phosphorus, nitrogen, carbon, a comprehensive formula, and more. I like their iron the best because it is cost effective and works well, and I like their potassium the least because it is not at all cost effective in my opinion, and it would be better to use their main ingredient , potassium sulfate, by itself in its dry form.
Other popular commercial liquids include Tropica’s Mastergrow. They have recently revamped their entire line, however, so the new name to look for is Tropica Aqua Care. I see that they have the new stuff over at BigAl’sOnline.com, as well as some of the old stuff.
You must carefully look at the labels when looking at other liquid plant fertilizers. Don’t pay close attention to the catch phrases on the bottle, or what it says it does for plants. Look at the contents and see what it is that is actually in that bottle. Many times, the wording on the front of the bottle would leave you to believe that it is all you need to grow healthy plants, when in fact it may only contain one or two nutrients and that’s it.
Dry fertilizers - Usually available from hydroponic stores or online places such as Rex Grigg’s for U.S. and Canada or AquaEssentials for those across the pond, these fertilizers must either be dosed by the gram or measuring spoon. The good thing about these are that you know exactly what is going in the tank and can control exactly what is being added to the aquarium. There are many online calculators to help figure out how much to dose of what or how much of a chemical to mix with how much water for making your own liquid fertilizer, but one of the most popular ones is by Chuck Gadd , which I have listed in my “resources” set of links. For adding something dry, you would just set the amount of water to “1″ ml. Distilled or RO water is typically used for mixing with these chemicals. When people mix up their own comprehensive plant formula using these dry chemicals, the result is often called “PMDD” or “Poor Man’s Dosing Drops”. The most common chemicals are as follows:
Plantex CSM+B - A dry trace fertilizer used for dosing micro nutrients. It contains 1.5% Magnesium (MG), 1.5% Magnesium (cheleted), 0.10% Copper (Cu), 7.0% Iron (Fe - cheleted),
2.0% Maganese (Mn - Cheleted), 0.06% Molybedenum (MO), and 0.40% Zinc (Zn - cheleted). Typically it is mixed at the rate of 1-2 Tablespoons per 500 ml or half-liter. Must be shook up before dosing each time.
Potassium Nitrate( KNO3 ) - Normal level of 5-20 ppm (approximately). We usually use this for dosing the nitrogen. Nitrates are a form of nitrogen. Many people use Potassium Nitrate for dosing nitrates. Some add it to their plantex csm+b mix because they know how many nitrates their tank sucks up , or at least a close enough guess. Others just add it dry at certain intervals, or measure it dry and then mix with a little bit of tank water before putting it into the tank so their fish don’t try to eat it. Commercial liquids that are used for dosing nitrates include ” Seachem Flourish Nitrogen”, among others. Sometimes, depending on the fish load, fish pooh is enough. Calcium nitrate is also sometimes used by those wishing to add calcium as well as nitrates.
http://en.wikipedia.org/wiki/Potassium_nitrate
Potassium Sulfate (K2SO4) , or sometimes potassium chloride ( KCl)- Normal level of 15-20ppm+(approx.). Usually just dosed dry or added to the plantex csm+b mix . We use this to dose potassium many times. Notice that potassium nitrate has potassium too, as does the next fert in this list, mono potassium sulfate. If you dose a lot of the potassium nitrate and monopotassium phosphate, it lessens or sometimes disqualifies the need to add potassium sulfate or other forms of potassium. Commercial liquids for dosing potassium include ” Seachem flourish potassium”, which is basically potassium sulfate mixed with water. Many of your commercial trace ferts will have potassium in them, but an insufficient amount for a high-light, co2 injected tank most times.
http://en.wikipedia.org/wiki/Potassium_sulfate
http://en.wikipedia.org/wiki/Potassium_chloride
Monopotassium phosphate-(KH2PO4)- Normal range of 0.5 to 1.5ppm(approx). - A little bit goes a long way, so it’s usually premixed pretty weakly with water and dosed by the milliliter. It’s sometimes added to the premixed plantex csm+b mix as well, but most like to dose it seperately, as with the nitrates.. Many people like to keep their nitrates and phosphates in a certain ratio to help maintain a more constant level in their tanks and to discourage algae accordingly. They refer to this as the NPK ratio ( Nitrates to Phosphates to Potassium). If I have 10ppm nitrates, 1 ppm phosphates, 20ppm potassium then my NPK ratio would be 10:1:20. If nitrates were 20, phosphates 2, and potassium 40ppm, I would still have a 10:1:20 ratio. I don’t get caught up in ratios too much, but it’s still good info so when people are talking about NPK you know what it means. Flourish Phosphorus can be used as a liquid fert, as can other things, such as Fleet enemas ( yes.. the kind at the pharmacy you stick up your @#$) to dose phosphates.
http://en.wikipedia.org/wiki/Monopotassium_phosphate
Iron chelate powder- (Iron Chelate Sequestrene 10%, etc.) : Normal starting range of 0.1-0.5 ( approximately), but some dose higher. Can be bought dry and added to your plantex csm+b mix or mixed straight at the rate of 3.53 ounces per 1 litre of water . You can also use flourish iron. Flourish compehensive has enough iron that it is used for dosing iron sometimes as well but that doesn’t work for everyone.
Magnesium/Calcium - (see below links for some of the possible chemicals):
As stated before, Magnesium and Calcium aren’t always needed as a supplement, depending on your tank’s water, or your tapwater for that matter. A GH of 3 degrees , or around 50ppm, or higher and you should be fine for magnesium and calcium, and with a KH of the same or higher, there should be no problems as far as your plants are concerned.
Check out the water chemistry section for more information on GH.
http://en.wikipedia.org/wiki/Magnesium_sulfate
http://en.wikipedia.org/wiki/Calcium_sulfate
http://en.wikipedia.org/wiki/Calcium_nitrate
http://en.wikipedia.org/wiki/Calcium_carbonate
http://en.wikipedia.org/wiki/Calcium_chloride
Substrate Fertilizers - There are a lot of different ways to fertilize a substrate. First of all, I must point out that not everybody keeps a substrate fertilized, preferring to fertilize the water column instead. Likewise, other people only keep the substrate fertilized and don’t fertilize the water column much. I have found that I have the most personal success if I fertilize both the water column and the substrate.
One way the substrate can be fertilized is by using a planted aquarium specialty substrate. Otherwise, there are fertilizer tablets which can be purchased in all sorts of different varieties that can be pushed down into the substrate, releasing nutrients over time. At almost any petstore you will find these, from very cheap to pretty expensive. Some people, like myself, make their own using a dry red clay and dry chemicals. I find that certain plants do a lot better with a fertilized substrate, such as sword plants, crypts, and so forth. Seachem’s flourish tabs work well, as do the cheaper AP Planttabs, and most any fertilizer tablet meant for aquariums will help somewhat.
How do you dose dry chemical fertilizers or commercial liquid fertilizers?
There really is no one right question, but if you have a co2 injected tank with medium high to high lights, I would suggest the EI ( Estimative Index) method, made popular by Tom Barr if using the dry chemical ferts. If using liquid commercial ferts you can still use this method, but you must tailor it to fit your needs. It is one of the easiest ways to do the dosing because it doesn’t involve you sitting over your tank testing the water with various kits every day. He also has a simplified version posted on his message board. If you have a medium to medium low light tank, you will probably be able to get away with maybe just a little bit more than is recommended on the bottle of liquid ferts, or with minimal fertilization with the dry chemicals as well. In a low light tank, you may be able to get away with practically no fertilization, or with just the recommended amount on the bottle, or maybe twice a week with dry chemicals.
No matter what you are dosing, commercial liquids or PMDD , the idea is to make sure your plants have everything they could possibly need at all times. Light, carbon (co2), all macro nutrients, and all micro nutrients. People scared to dose fertilizer for fear it will give them algae almost always end up causing what it is they are trying to prevent by their hesitation. Don’t be scared to give the plants everything they need to grow.
Greg Watson, a great contributor of cheap nutrients for the planted tank hobby for years, has a guide out that outlines dosing strategies. I strongly recommend it for the beginning planted tank hobbyist. You can find out more at http://www.aquaticplantnews.com/
Here is a “what the heck is that chemical?!” table to help you go by. May not be 100% scientifically accurate, but it is the usual online jargon:
KNO3 - Potassium Nitrate
K2SO4 - Potassium Sulfate
KH2PO4- Mono Potassium Phosphate
MgSO4 - Magnesium Sulfate (MgSO4ยท7H2O is the actual terminology for the magnesium sulfate we use, but it is seldom used).
Ca(NO3) - Calcium Nitrate
CaCO3 - Calcium Carbonate
K2CO3 - Potassium Carbonate
KCl - Potassium Chloride
K - Potassium
Fe- Iron
N - Nitrogen
P - Phosphorus
( More to follow)
I am just a hobbyist trying to help other hobbyists. If this site helps you at all, or you have more questions, or have comments, please contact me. Thanks!