[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Osmocote

I don't know a heck of alot about water chemistry or for that matter, slow
release fertilizers but apparently I know more about slow release fertilizers
than most of the folks that have been posting so far.  Osmocote and most
other slow release fertilizers' (e.g., nutricote, polyon, etc.) timed
fertilizer release is based on the fact that the fertilizer is coated in a
semi-permiable polymer coating.  The fertilizer release (at least in
terrestrial environments) is influenced greatly by temperature.  Generally
the products will be sold by their analysis and time release characteristics
(e.g., 14-14-14, 3-4 month formulation).  The release time is based on an 80%
nitrogen release at a given temperature (each company uses their own standard

Some of you may recall my postings awhile back where I added a slow release
fertilizer (Nutricote) to my substrate when I started my 75 gallon tank.  I
have run into several problems using this technique.  First, it seems the
fertilizer released a large amount of ammonium up front so I could never
trust my ammonia test results (levels stayed at 7 ppm+ for several months and
have finally dropped to 0.5 ppm in the last couple of weeks).  In spite of
the high ammonia levels I never experienced any problems with my fish.  I had
a terrible green water problem to start the tank off (may be incidentally
related to the fertilizer application).  Presently I am having a pH problem
which I am fairly sure is related to the fertilizer application.  In spite of
the problems I am happy, so far, with the results.  My plants are lush and
growing and, for the most part, my fish have been healthy.  A couple of
things I would change if I started over.  First, I based my fertilizer
applications on terrestrial plant recommendations.  Given that an aquarium is
a relatively closed environment I probably should have reduced that amount by
1/3 to 1/2.  Second, many slow release fertilizers include a micronutrient
charge, I would make sure I used a fertilizer with micronutrients (not need
to worry about PMDD).  Third, I would probably use a fertilizer that didn't
utilize ammonium as its major nitrogen source.