Re: blocked on nitrogen

Matt Rhoten writes:
> I'm convinced my aquarium's plants' growth is blocked on nitrogen.

It is a very common problem together with potassium deficiency.

> I have a nutrient-poor gravel substrate. Short of a
> complete teardown and substrate change what are the optimal ways
> to add nitrogen?

I don't think one can rely upon the substrate to supply all the
nutrients indefinitely. Studies have shown that potassium and
nitrogen can be supplemented quite effectively in solution. I would
strongly suggest that you investigate the PMDD recipe and instructions
which many folks have been reporting excellent success with.

Another strategy which may be effective for substrate enrichment
is the use of a small amount of slow dissolving fertilizer tablets
or sticks inserted into the substrate about every six months or so.
I must stress that this is experimental and that you could easily
create a very bad situation by adding the wrong kind of fertilizer
or by adding too much. I have used Jobe's fertilizer sticks
(about 8 broken into small pieces in a 50 gal tank with 3 inches
of gravel at about 6 month intervals) Jim Kelly has used Osmocote
tablets or pond tablets with a smaller number broken into small

> Is safe dosing with an ammonia fertilizer possible? 

I doubt it. Stick with PMDD, the ingredients are pure, extremely
inexpensive and the dosage has been worked out properly. Leave
experimentation to the experts.

> I've seen blood
> meal used with terrestrial plants; its main fertilizer component is
> nitrate. 

Please don't start sticking things like bananas or other complex
organic compounds in your tanks! All of these things can create
toxic conditions and encourage the growth of harmful bacteria.
If you wish to use organic components, the safest of these are
soil (used 1:20 in the lower 1/3 or perhaps 1:5 if you are prepared
to deal with balancing conditions to avoid algae) or peat. You
should also be aware that some soils may be unsuitable and we
should have some guidelines to help DIYS soil collectors.

A number of us are working diligently on a substrate FAQ which
will contain procedures for a wide range of substrate types.
If you can wait for another month or so, it should be available
then. :-)

Steve     Vancouver BC