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Nutrients + Equilibrium?

I've been following Tom and Roger's posts with great interest re dosing with
KNO3, K2O4, KH2PO4 - was wondering what tank size the 1/4 teaspoon of KNO3
referred to?  

Finally found a place that stocked and bought myself some of all of the
above, as paying $15 per week for a large bottle of Flourish Potassium was
getting to be too much!  Couldn't wait to experiment, of course, so I
started (after doing my usual weekly major water change, ie 0 nitrates) by
mixing a cup of water with 1 teaspoon KNO3, 1/2 tsp K2SO4, 1/2 tsp KH2PO4,
and adding a little to my low light 25 gal, no nitrates, so I added double
my dose, still nothing.... etc etc, til I had added about half of that cup.

So then I mixed 4 tsp of KNO3, 1 tsp K2SO4, 1/2 tsp of KH2PO4 in a cup of
water, and put 1/4 cup of that in, still no discernable nitrates, but
checked the P, wheeew, way high (about 6 on Hagen test kit)! So the KH2PO4
does need to be added VERY judiciously, duhh, it is a finer powder, how much
is half a gram anyway! :)

Didn't have time to do a water change right then, so decided to add a bit
more nitrate and potassium via KNO3 to at least try to balance the P, about
2/3 of a flat teaspoon - next day, nitrates about 7, P still way too high,
also about 7.  So in total, I must have added about 2 tsp minimum of KNO3 to
my 25 gal tank - was it just starving, as I did it over several intervals
with a couple of hours inbetween, and it all got absorbed instantly?  the
plants don't look too much different, just redder from all the P!

I tend to have P levels much higher than N, btw about 1 and 3 by the end of
the week; N is about 3-6, so it could go up a little more.  Carbon could go
up a little more, so I've been adding more of that lately, to give about
12mg/l in my low light tanks, about 15 in my med light tanks - still low,
and I will take it a bit higher.

The next question is what do I do about using Equilbrium, which I have been
using to provide traces and also to get a GH of 8-12 in different tanks - I
also bought a trace mix at the hydroponics shop where I got the other stuff,
which may not be suitable for aquarium use, it has copper in it:

iron 5%, manganese 2%, zinc 0.4%, copper 0.1; then it says actual iron 2%;
boron 1.3%, molybdenum 0.06%, and EDTA 42% + DPTA 13% (chelators) - is this
suitable, and if so, how much would you suggest for a 20 gal, heavily
planted and fed, med light tank?  I can never get iron readings except in my
lower pH tank, which stays steady at about .1-.2, but I have a rich soil
substrate in all tanks, so I haven't worried about it, the plants, as far as
I can tell, aren't deficient.

Equilibrium has potassium 18.9%, magnesium 4.3%, calcium 2.7%, Fe 0.47%,
manganese 0.08%.

The potassium I was adding in a big way in the liquid form, less meant holes
in leaves, so it was being added only to just over the minimum (40 ml per
day in 25 gal tank).  Magnesium and calcium are also being provided by
dolomite; so I guess all the Equilibrium is really adding is the iron and
manganese, so if I use a trace mix instead, that should make it
unneccesary.......sugar, and I just bought a big bucket of the stuff for $75
a couple of weeks ago!!

Other info - my tap water is very soft, pH about 5.5, no KH or GH or
calcium, so I add baking soda for KH to about 4, Equilibrium as above, and
dolomite to give me 40 mg/l of calcium, with very heavy feeding for the N
and P (4 times a day in my big soft water tank, 5-6 times a day for the
guppies, liberal amounts).  I found I had to add the K to balance this.

Part of the impetus to try a new regime was that the plants in my big 80 gal
soft water tank (med light) have slowed down a lot in the last few weeks,
and I'm getting some bits of hair algae in my med light 20 gal, so
something's missing!  I also moved house a couple of months ago, so maybe
its a delayed reaction - both tanks were getting a bit more sun in the other
house (I moved them with soil and plants intact).

Any comments welcomed, kind regards,

Susi Barber