Paul Sears wrote:

>	I am now of the opinion that if there is little nitrate in the 
>water supply and no major source of potassium in the substrate, most tanks
>short of potassium.  This then means that the plants cannot use the 
>nitrogen, and nitrate builds up.  I think that a lot more tanks would be
>"nitrogen limited" if potassium were supplied adequately.

Another point in favor of Mastregrow for those who don't want to fine tune
their own formula.
Mastergrow contains relatively large amounts of K and Mg as well as much
smaller amounts of trace elements.

Paul also wrote:

>> I'm not disagreeing with your
>> approach, or your advice.  But I also know how many beginner aquatic
>> gardeners _start_ with high nitrate levels.
>	If they have no nitrate in their tap water, they are short
>of K, trace elements or both. 

Not if they are even shorter on light, which is very often the case.

>  I wish people would _read_ what we
>wrote rather than using another fertilizer recipe blindly.  Only
>add the nitrate if you can drive the tank nitrate to unmeasurable
>levels.  This is not difficult.

I have, and I understand your point.  But I've also been working with
enough planted tank beginners for long enough that I have to be realistic.
No matter how carefully you word something, whether in writing or a
lecture, SOME of the people are going to latch on to some (possibly totally
insignificant piece of information) and miss the whole point of what you
are trying to get across.
>> BUT at the same time, I
>> think it's usually safer for beginners to go the laterite/ liquid trace
>> element route, since I ASSUME that most of them will over stock and over
>> feed, under plant and under light.<g>
>	If they do all those things, I think they are sunk anyway!  Start 
>with K and trace elements (I'm not sure what, if anything, laterite does),
>and use nitrate if required.  It is not complicated, but one _must_ use
>enough potassium, and I think most don't.

Here, I'm sorry, but you are absolutely wrong.  While your method may be
more scientific, and possibly easier if you understand what you are doing,
I _guarantee you_ that there are many people who are fairly clueless, but
are maintaining beautiful, healthy planted tanks that are relatively algae
free using laterite and a good trace element supplement, depending on fish
food/waste as the major source of NPK.

>> Sometimes we forget, here in the list, that by the time someone makes it to
>> this list, whether they seem like "newbies" to the really experienced folks
>> or not, that they are already light years beyond the "average" hobbyist.
>	I think the problem is that the subject has been something close
>to a black art for a very long time.  "Fertilizers" and other additives
>with unlisted ingredients, lots of conflicting stories about what causes
>what, and an appalling ignorance of basic chemistry have left almost
>everyone in the dark, hoping to find a set of conditions that lets
>them keep a half-way decent looking aquarium.

I have to agree with you completely there.

>	It does not have to be like that! 


Karen Randall
Aquatic Gardeners Association