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Re: K2HPO4 (or KH2PO4)
Tom Barr wrote:
>> It all was made possible by PO4 and Tom Barr's constant nagging and
reminding
>> to the point where I finally listened.
>
>Careful. Neil has reminded us that we(well okay just me,) have becomes pious
>plant zealots that have run amuck. Some folks only want one sword plant in
>that 75 gallon tank or enjoy stunted plant growth.
There are other choices between one stunted sword and a weed choked jungle
of fast growing stem plants.
>Stunted plants growth, using a P limited approach is STILL very effective
>but the P is not meant to go to zero just low relative to the other
>nutrients.
Many, many plants will do just fine with unmeasureable P in the water
column. If unmeasureable, it doesnt mean you dont have sufficient P: (a)
the plants may have already sucked up and stored the P provided from your
tap water and fish food, They can then recycle this nutrient from old to
new growth... you might just see a few dying leaves here and there, and
(b)there can be lots of P in the substrate (bound to laterite, soil or mulm).
HOWEVER, because of Tom's prodding and my earlier discussions with him and
Steve Dixon about the virtues of playing with P to turn colors on and off,
I ordered some KH2PO4 (monopotassium phosphate - one K, two H's), and have
recently started to add it ( together with K, N) to some of my tanks.
BINGO! The plants have not looked this good in years. They are also
growing out of control, so I am going to have to figure out how to slow it
down a bit! One is a 2 month old setup - the small amount of spot algae is
completely gone. No visible algae AT ALL. These 2 tanks get 2.5 watts per
gallon - they are my "high" light tanks.:-) My other 2 large CO2 injected
plant tanks have less light (1-2 wpg), and they have responded a bit
differently to the trial P injections. In the 1wpg tank, some "string"
algae has appeared. It is really crowded with plants which limit water
circulation. If I remove some plants, I probably could reduce/eliminate the
algae. The other tank has the thin bladderwort (Utricularia) and the extra
P has made it go nuts. Tom, can removal of bladderwort be your doctoral
disertation?
BTW, when I add K and N with the P, here is my formula for 100 gallons:
1/4 tsp of calcium nitrate (1.5gms)
1/4 tsp potassium nitrate (1.4gms)
1 test kit measure of monopotassium phosphate (.03g)
This gives me: the NPK ratio I am shooting for - more N and less K than I
can get with KNO3 by itself.....a little extra calcium for my mineral poor
soft water ...(I also add lime with each water change)..... no K2SO4...my
tap water has 10-20ppm SO4 and I dont want too much K because I have soft
water and I can get lazy and not add lime so my GH drops.
>I'm not sure if your helping or hurting the Tom and Neil issue.
>Neil's very correct on many issues.
Just many?? :-)
Neil