Ferts are confusing to me .. - The Planted Tank Forum
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post #1 of 5 (permalink) Old 09-20-2014, 01:42 AM Thread Starter
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Ferts are confusing to me ..

hi folks - i recently picked up the Liquid NPK + M and GH booster from a seller here in the forums.
But i see people mention that they dose "traces" and "nutrients" and "EI", etc.,etc.. ...
are all these included in the solutions that i purchased or are these things that i need to be looking to pick up?
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post #2 of 5 (permalink) Old 09-20-2014, 02:08 AM
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Without knowing what is in the things you bought I am not sure. However, here is a quick rundown on ferts.

Plants use over a dozen elements to survive. Some they use in large amounts, others they use in smaller amounts.
Some are supplied in other things we are already adding to the tank (like fish food), others are in short supply and need to be added as fertilizer.

Hydrogen (H) and Oxygen (O) - If your tank is lacking these then this thread won't help

Carbon (C)- Plants use more carbon than all the rest of this list. Carbon is best supplied as CO2, but can be supplied in liquid form like Seachem Excel. Fish breathing supplies a very small amount. Water takes in a small amount of CO2 from the air. Biological processes like decomposition add CO2 to the water.

The next 3 are grouped as Macros.
Nitrogen (N)- Plants use a lot of Nitrogen. Aquatic plants can use it in several forms. Nitrate, Nitrite and Ammonia. Fish food supplies a certain amount of nitrogen. Protein includes nitrogen, and when it is broken down in a fish's digestive tract, or decomposed by microorganisms some of it ends up in a form plants can use. You can test the NO3 and tell if you need to add more to keep the plants happy.

Phosphorus (P)- Plants use a lot of phosphorus. Not as much as they do of nitrogen, but still enough to call it a macro. Fish food adds a reasonable amount of P to the tank. If the NO3 from fish food is enough, then it is reasonable to assume the P from fish food is reasonable, too.

Potassium (K)- Plants use a lot of potassium, and there is not as much in fish food as the plants need.

The next 2 are secondary nutrients, measured with the GH test.
Calcium (Ca)- Often comes into the tank in tap water, if the GH is over about 3 degrees. If there is any question about this you could do further testing. If you are using reverse osmosis or distilled water then you will need to add Ca. Fish food does not have much.

Magnesium (Mg)- Plants need about 1/4 as much Mg as they need Ca. If the GH is over about 3 degrees then you could assume there is enough magnesium. But if there is any question you can do further testing. If you are using RO or distilled water then you will need to add Mg.

GH booster is a source of both Ca and Mg, and usually K. Read the label, there are different formulas. Make sure the product you buy does not have salt (Sodium chloride).

Iron (Fe)- Is the other element that plants use in a large enough amount to almost call it a secondary nutrient. It is often included in trace or micro blends, but some people like to add more. Fish food is low in Fe.

All the other minerals that plants need are required in such small amounts that they are lumped together as micros or trace minerals. There is a reasonable amount of pretty much all these in fish food.


If you are running a tank in a low tech method, Diana Walstad method or similar, then the plants are growing slowly, and need only low doses of fertilizer. Perhaps their needs can be met with tap water, fish food, and just a couple of added nutrients. Usually K, Fe and Carbon. The carbon in a low tech tank is often liquid (seachem excel) or DIY method of yeast and sugar.
You can test the water for NO3. If the level is climbing or holding stable between water changes, then the plants are getting enough of most things from fish food. K, Fe and C were the first 3 things I added to the tanks as I learned more about planted aquariums. They are the first 3 things most planted tanks run out of.

If you are running the tank in a high tech system, you are adding pressurized CO2, higher light, and the plants will need a full dose of all the fertilizers.
The tap water might still supply the Ca and Mg, but monitor it. If the GH is low to begin with, and the plants use so much the level falls between water changes then you might have to add some.
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post #3 of 5 (permalink) Old 09-20-2014, 02:24 AM
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Diana you always make such wonderful, informative posts.

Luky - If you mean the liquid NPK and M at the top of that post you linked, then what you have is a full range of ferts. The NPK are macros. M is micros, aka traces. Follow the dosing schedule appropriate for your tank that Nilocq lists and you should be good to go.

EI is a routine based on specific amounts and water changes. The dosing amounts given for those liquids are based on EI levels. See this thread for more details The EI concept Explained

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Last edited by burr740; 09-20-2014 at 03:13 AM. Reason: .
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post #4 of 5 (permalink) Old 09-20-2014, 03:22 AM Thread Starter
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Diana, burr740 ..
you guys rock!! thanks so much for all that!
im a little slow, so it'll take some time to get there ... but i get there.
thanks so much.
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post #5 of 5 (permalink) Old 09-20-2014, 09:53 AM
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Luky, I even learned from this thread; So I'm thankful for it.
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