# NPK fertilization



## caywood (Apr 14, 2004)

Hey folks,

I have a question as to whether it is necessary to add nitrogen, phosphorous and potassium to my planted tank.
I have a relatively new 100L tank set up for a little under a month. I'm running CO2 with digital control (I maintain the pH at 6.7 with a GH of 4-5 and KH of 2) and also dose Duplaplant 24 continuously via a feeding pump to keep an Fe(II) concentration around 0.25ppm and add Duplaplant tablets at weekly water changes. Everything is growing pretty well, but I never observe O2 production on my Riccia---there is plenty of light available (~5W/gallon with 65W compact fluorescents 50/50 6500K/10,000K) So, I gather there is some nutrient deficiency that hinders the rate of photosynthesis. The thallus of the Riccia is also a lighter shade of green than one generally sees (e.g. in Amano's books). 
I have never added N, P or K to my tanks in the past since I assumed these nutrients would be available compliments of the fish. However, this is my first setup with really heavy planting and CO2 injection. I prefer not to measure a bunch of different nutrient levels, but to judge things by the health of the plants. I have a slight algae problem already on the slower growing plants along with some annoying hair algae that I am constantly pulling out of the hairgrass in my tank (seems to have arrived with the hairgrass---perhaps I accidentally ordered the "hair assortment"??) 
So, I'm a little wary of adding phosphorous for fear of algae explosion. 

I'm interested if anyone has recommendations for me (what product to use etc.) Also, I'd like to add whatever fertilizer I do use to the duplaplant 24 dilution so that it is added constantly in small amounts---is there a problem with mixing fertilizers in this way? (I worry about precipitation of the iron or other unwelcome reactions). I bought some Tropica Mastergrow recently, but from reading the label I gather this is a similar product to Duplaplant-24 and not a solution to my particular problem.

Any thoughts would be appreciated,
Regards,
Caywood


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## Sir_BlackhOle (Jan 25, 2004)

I think that the dupla drops are trace elements correct? What is in the plant tablets?

I would recommend dosing NPK in a tank with high light/CO2 injection like yours. I use Greenlight Stump Remover, which is pure KNO3. You could also order it from Greg Watson at http://www.gregwatson.com/ for real cheap. Use the info found on this page http://users.ev1.net/~spituch/Chemicals/chemicals.html to determine how much you need to add to arrive at 5-10ppm N. Hope that helps you some 

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## plantbrain (Jan 23, 2004)

At 5w/gal, CO2, fish load alone is not enough.
You will have troubles till you add enough NPK.

KNO3 is cheap, easy to find.
KH2PO4 is similar

These are all you likely need along with the traces(you need more than merely Fe).

For a 100 liter tank: 
Add 3x a week, 1/4 teaspoon of KNO3
Add 3x a week, roughly 7mls of Tropica Master grow etc
Add about 1-2 rice grain's worth of KH2PO4.

Lower your pH down to 6.3-6.4.
You do not have enough CO2.

The CO2 is only 9ppm or so presently.
20-30ppm is what you should have for the entire lighting period.

PO4 Fe etc can appear to cause algae, but it's CO2 and NO3 most often that cause the real problems, such is your case and most cases.

You do the routine I suggested, you will see Riccia pearl.
Do large weekly water changes also, this will keep the nutrients from getting too high and the frequent dosings will keep anything from running out.

The 1/4 teaspoon will add about 7ppm of NO3 to your tank per dose of KNO3.

If you wish to rely on fish waste for nutrients or a larger share, try non CO2 methods and much less light.much less light.

2 w/gal is fine.

Regards, 
Tom Barr


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## caywood (Apr 14, 2004)

*Thanks*

Tom,

Thanks for your suggestions---exactly what I needed to hear. I'll give these a try and post results in a few weeks.

Regards,
Caywood


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## plantbrain (Jan 23, 2004)

You will see improvements immediately, within 3 weeks, your tank should be humming along nicely.

Always work from how much light and then to CO2, GH, NO3, K, PO4, traces. Check this order before proceeding to the next one. 
CO2 and NO3 will burn you more than the others.

Main thing is the CO2 but with a pH probe and good measurements, that will not be much of an issue.

Regards, 
Tom Barr


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