Re: Nitrate deficiency

Joanne wrote:
> I've been noticing that every time my nitrates get down to zero in my
> planted tanks I get a yucky brown slimy sludge growing.  I'd like to
> know if anyone else has encountered this.

These are diatoms I suspect. Odd however if you have plenty of light
and catfish to stir up the bottom and good water circulation to keep
detritus from accumulating too much on the bottom. Perhaps it is
uneaten food and fish poop? I don't know if it is right to associate
zero nitrates with this.

> I've also been having problems keeping my nitrates up!  My tanks are
> fairly well stocked but nitrates keep dropping to zero.  I have recently
> tried adding a nitrate containing fertilizer (Plant Tabbs) but these have
> more phosphates than nitrogen.  I had to add 6 to my 25 gal tank to get
> up to 3 ppm nitrate but that went to zero the next day.  In the meantime
> I now have about 0.8 ppm phosphate - no algae bloom yet & I'm keeping
> my fingers crossed.
> I have decided to add just some calcium nitrate (Ca(NO3)2) and some
> potassium nitrate (KNO3) along with some magnesium sulphate (MgSO4) -
> basically Hoaglands Solution without the potassium phosphate (I will
> double the amount of potassium nitrate to get more potassium).  I have
> ordered these chemicals from a chemical supply company (Sigma).
> Does anyone forsee a problem with me doing this?  or can you suggest
> any other solutions? (I'm already overfeeding my fish).

If you have plenty of fish there should be no shortage of Nitrogen
in the form of ammonia for the plants. Nitrate is a sign the plants
cannot cope with the amount of ammonia and other bacteria are reducing
it to nitrate. I think you want to reduce feeding rather than continue
over fertilizing. Better to keep the rate limiting factor nitrates and
phosphates not plants, CO2 and light. Perhaps someone can suggest another
remedy for the brown sludge. What is your pH and other water parameters?
Perhaps you might have more green algae with more light.

- Steve