Re: adding nitrates

>Karen's response: Re: Phosphates 
>Kevin Conlin wrote:
>> At the moment you are probably nitrate limited as shown by the g
>> of cyanobacteria.  KNO3 alone will probably help, but once you a
>> there is the possibility that the plant growth will be limited b
>> other than phosphate.  This is why Paul and I recommend adding t
>> whether you think you need them or not.  Try adding a 1/4tsp KNO
>> your nitrates into the 10ppm range and see if this helps.  If in
>> the cyanobacteria are replaced by green algae, you will probably
>> K2SO4 and/or trace elements.  Once you've tweaked the nutrient l
>> your tank you should see very little algae of any kind.
>I have OFTEN seen cyanobacteria present even with high nitrate 
>levels.  I also am not sure it's a good idea to suggest adding 
>nitrate to the average planted tank containing fish.  In a tank 
>without fish, it is certainly possible to end up with a nitrogen 
>deficiency. But in tanks with even a fairly light fish load, there 
>is usually plenty of nitrogen available to the plants. 

Maybe my light fish load is VERY light, or I do not feed enough (or my plant
density is relatively higher), but I often observe nitrogen deficiency. I
know this because the duck weed (indicator plant)looks pale and is not
reproducing. After adding 1-2 grams of NaNO3 (Nitrate of Soda, from garden
store), the plants perk up, including the duckweed. BTW, 1/8 teaspoon is
approximately equal to 1 gm and yields a concentration of 1ppm in 300 liters.
I also think that adding the nitrate will help consume excess phosphates.
(but it will also consume Potassium, and everything else, but it looks like
Keven has already taken that into consideration.
>recommending a nitrate level of 10ppm is asking for trouble.  Some 
>people, with other parameters just right, get away with it, but 
>I'm fairly certain that it doesn't contribute to good plant growth 
>as long as ammonium is available, and it _can_ cause algae 

I think that a few ppm of N is plenty!

>That's one reason that I wouldn't call the DIY fertilizer "poor 
>man's Dupla drops"... Dupla drops do _not_ contain nitrate.

How about "lazy aquarist who staves his fish drops"

Neil Frank                 Aquatic Gardeners Association,  Raleigh NC