On Fri, 26 Sep 2003 15:20:36 UTC, Blarneytoad
wrote:

I've tested my tank and nitrate and phosphate are almost
imeasurable.Plant growth is just not what I'd like so I've decided
to dose those two compounds.I can't find any greenlight stump
remover so I'm going to try Seachem's new nitrate and phosphate
additives. Has anybody tried these yet?

Perhpas I'm years out of date, but I'd think twice before adding
phosphate. See
http://www.cam.org/~tomlins/algae.html
which describes actual experiments (so rare in this business!) and
concludes that keeping phosphate down to virtually nothing is the way to
starve algae while growing healthy plants. Higher (vascular) plants
appear to be extremely good at using low levels of phosphate.

By the way, what tests are you using? I've bought a couple of phsophate
kits and found that they just couldn't detect phosphate! Probably
outlived their shelf life or something. Anyway, I could make a phosphate
solution in the range they were supposed to measure, or way above it, and
they wouldn't register. The expensive kit that I use now (Lamotte) always
detects a solution of 1 mg / l or whatever.

(However, I think the Lamotte low-level phosphate kit stinks. Its color
samples are entirely different from the colors the test generates. This
is not good enough for fifty bucks or so. I now run double tests
routinely, one being a calibration with a known PO4 concentration. Does
anybody know of a *good* PO4 test at any price?)

Anyway, why not try adding just nitrate first? I currently add a small
amount of nitrate daily, to keep up the level that's recommended on the
web page I listed. (0.5 cc of 10% KNO3 today, but still trying to get it
to a consistent level.) If your plants don't pick up, and your lighting
is good, and you're sure you have enough iron and potassium and other
things, then try phosphate.


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