# How much fertilizers for a 20 gallon tank?



## saeisbest (Dec 20, 2015)

I have a 20 gallon long with a Betta and several neons. Currently, I am running a 15 watt light on this tank. I will be running more lights once I know how much to fertilize. There are two other light strips that give this tank 47 watts. I have an eco-complete and seachem fluorite substrate mix. I have API CO2 Booster and root tabs. I have the following fertilizers-
K2SO4
KNO3
K2PO4
CSM+B
I also have measuring spoons available. So how much for this tank?


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## Diana K (Dec 20, 2007)

You seem to be asking about 2 different things. 
Current tank is VERY low light, so it might be that fish food is enough, especially with the slow release of fertilizers from the root tabs. 
Your new set up will have a lot more light, so will require more fertilizer. How much more will take some work. Try one of these systems, and see if it works for you.

There are several methods of fertilizing. One is called the Estimative Index. The concept is to provide plenty of all the fertilizers, then do a big enough water change each week to remove most of whatever the plants have not used. With the extremely low light now, I would try half this recipe, but still plan on 50% water changes. See if that works for your tank. I don't even know if your current set up needs any additional fertilizer.

(From the sticky at the top of the Fertilizer forum)
20~40gal
50% H20 change-weekly
1/4 Tsp-KN03 3x a week
1/16 Tsp-KH2P04 3x aweek
1/2 Tsp-GH booster once a week 
5ml or 1/16Tsp-Trace 3x a week (CSM+B can be dosed equal to the KH2PO4)
Optional
1-2ml-Fe/Iron 3x a week (Chelated iron can be dosed at 25% of the CSM+B)

Generally the ferts are added in this order:
KNO3 + KH2PO4 + K2SO4 (if needed) on Monday, Wednesday, Friday
CSM+B and Iron (if needed) on Tuesday, Thursday, Saturday
Water change on Sunday. If the tank needs GH booster add it with the water change.

Here is more info. 
http://www.plantedtank.net/forums/11-fertilizers-water-parameters/21944-_dosing-regimes_.html

You could further modify the EI method and do smaller and fewer water changes, but you would have to figure out the exact amounts. Start with the same ratios as the EI recipe, but use perhaps 1/10 as much of each. 
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Another method is referred to as PPS-pro. 
The basic thought is that you supply barely enough fertilizers for the plants. No big water change is needed just to remove the excess fertilizer, but a reasonable weekly water change is good.

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You say you are already using root tabs. What elements do they supply to the plants? Do any of these show up when you test the water?

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Fish food supplies most of the elements plants need. 
Fish food is low in potassium, iron, calcium and magnesium. 
Water with GH of at least 3 German degrees of hardness will usually supply enough Ca and Mg. You could dose some GH booster if you thought these levels are too low. 
For the low tech way your tank is currently running you might only need potassium and iron (K2SO4 and chelated iron), and these only if the root tabs do not have these elements.


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## Maryland Guppy (Mar 5, 2015)

saeisbest said:


> I have a 20 gallon long with a Betta and several neons.


Can you also mention the plant load/quantity.
We have no idea how many plants you are trying to provide nutrients to.
Pics are always wonderful to.


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## saeisbest (Dec 20, 2015)

Will seachem equilibrium work for GH booster?

Right now not much is in the tank. I have anubias, java fern, pearlweed, etc. Most of these are stray plants so it's a very small plant mass. But soon I'm getting a huge shipment of plants. 30-50 plants of jungle val and 30-50 plants of Ludwigia repens.

The root tabs are API root tabs although I am not sure what nutrients they have. The product claims it gives iron to plants.


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## niko (Jan 28, 2004)

What brought you in this hobby is what brings most people to it - the looks of Japanese tanks.

Not a single one of them uses any of the approaches described above.

Try to find out what the Japanese do. You will save yourself a world of frustration. No, it won't be too easy to find that information. The information that is easy to find is also 99% worthless. Keep that in mind.

Good luck.


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