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re: Karen`s System ?

Karen wrote: Anything pressing that I didn't mention?

Yes, you haven't specifically mentioned potassium supplements. Do you
find it rarely necessary to supplement it? Is it found in your tap
water? When you do feel the occasional need to add a nutrient, what have
you added? (aside from TMG) I know that TMG has K but (in my situation)
I think it is inadequate for a strongly lit tank with no shortage of N
or P. Put another way, the ratio of Fe to K is too high. Same comment
for PMDD; too much Fe and other trace nutrients.

Another suggestion for a cookbook recipe for plants is to start with as
much information from the local water utility as you can get. This will
tell you if calcium, potassium, magnesium are going to be lacking. Few
places have tap water low in these minerals but it can be frustrating if
you don't know it. All of the above are macro nutrients. Sulfer is the
"Other" macro nutrient we almost never mention because it's plentiful in
fish food and commonly as an ion (sulfate) in tap water.

BTW, potassium shortages are easy to spot; yellow spots and dying older
leaves so its easy to add a bit of K2SO4 and cure a tank for a very long
time. I would suggest 1/2 tsp in 40 gals to increase the potassium
concentration by about 10 ppm when its short.

I guess we should also point out that your (APD reader's) nutrient
strategy will also be affected if you use soils, peat or substrate
fertilizers of various kinds.