Re: Fertilizer

On Thursday, 21 March 1996, Andrew Hamilton wrote:

> In light of the recent re-post of PMDD's I have been wondering if the people
> that use these actually still use Slow rlease fertilisers that are added
> weekly or with every water change? Can I get by by purely using Duplarit (or
> whatever they call the gold dust) and PMDD's??? 

PMDDs are intended to be a complete (with the exception of P)
fertilizer.  Don't use anything else, except possibly a few slow-release
P-enriched tablets deep in an inert substrate (and don't use these if you
have a UGF or you're new at the game).

> What about the recent post on the analysis of fertilisers, has this been
> done scientifically or is it just speculation.

My table is based on published concentrations for the Tropica
fertilizer and both trace element mixes.  The Dupla concentrations are
taken from Mr. Booth's analysis (follow the links from the Krib home

> George, if Dupla Drops are
> purely Iron why on earth are they so expensive?

They charge extra for the lead (present in higher concentrations than
some of the essential trace elements).

> Is Dupla saying that plants
> only require Mg, Mn and Fe. Shorly their fertiliser regieme consists of more
> chemicals than these.

The tablets contain K as well.  My table shows only the micronutrients and
trace elements.  Tropica contains K, as does PMDD.  PMDD is the only
mix that also contains N.

> I have been using an Australian made Aquarium fertiliser for some time now
> that seems to provide enough of everything but iron. I dont use daily drops.
> Im going to make some PMDD's but wonder if I should continue using the
> current fertiliser.

Don't use anything else if you're using PMDD.  Not even water conditioners
unless they're simple dechlorinators.  Some conditioners specifically claim
metal-binding capability, and some may contain phosphate buffers.

> I will have to look at the ingredients. Only tests will
> tell what to do I suppose.

Always test.
> Surely no one fertiliser is superior to the other.

Some are clearly inferior.

> On any given day plants
> will grow at a different rate and therefore require a differnet amount of
> elements than the previous day.


> With that said fertilisers should be aimed
> at providing an average amount of each element required for excellent daily
> growth. Therefore, wouldnt PMDD's be the best fertiliser on the market
> (provided that the average of chemicals is taken from a large test???)

PMDDs should be tuned to your tank requirements.  The published recipe works
well in my tank with my substrate, lighting, plant mix, fish load, etc.
Once tuned, they should be superior to commercial mixes used as directed
(although you could tune these too to get the best results) because the
manufacturers can only design for average tank conditions. 
Kevin Conlin   kcconlin at cae_ca   "We're Canadians.  We HAVE to be polite"
Finger as332 at freenet_carleton.ca for PGP public key.