I answer from my humble experience only.....
After losing a massive amount of java fern due to k def. while dosing only kno3, and reading time and time again that
potassium overdose is about as dangerous as powerful sneeze, I've decided that dosing k2so4 can really only help things
This rings especially true for me as the plant mass of the tank becomes larger and larger, the potassium demand grows
similarly. Thus, why risk it? Just make sure you have plenty of potassium and it's one less thing to worry about.
Iron I liken to icing on the cake. If you can get the plants enough light, co2, flow, nutrients and everything the picky
little sob's need to thrive, and in the right proportions, the demand for iron can be enough to cripple your plants. Iron is
needed to produce chlorophyll and thereby, that lush green that those jaw-dropping tanks in the pictures always seem to
Don't just think, "hey my plants are looking a little on the lime green side, time to dose some iron" that line of
thinking leads to trouble. I have seen this by growing s. repens submerged and emersed. Emersed the repens is dark green
the very picture of health. It's growing in dirt and has access to "infinite" co2 being emersed. Submersed the repens
is clearly healthy and growing at a nice pace, but it has a lime green quality to it that bugs me. I've tried dosing a truckload
of iron to fix this, but it seems to have no effect.
The conclusion I draw from this is that the major difference must be co2. I suspect that if I were to seriously crank the co2,
the repens would oblige me with that dark green, but I would also lose my fish. I am working on slowly increasing the co2 and it's
helping. Most important thing to remember when bumping co2 is oxygen.......
Plants need iron to be sure, but they don't need an incredible amount, just a constant supply so they can use when they
need it. I've read that the "constant supply" part becomes problematic with certain types of chelators because they break down
quickly and differently according to ph. I dose iron when co2 has dropped my ph just in case.
From reading the dosing strategies from those amazing tanks, I've found that they typically dose k and fe daily. My point
is that this only helps when the plant actually needs those, that is to say, when the plant is healthy enough to have the ability
to use the fe.
If the plant suffers from co2 def. then adding a bunch of iron will likely only add to your troubles.
Now if you can put all that aside, I dose kno3, kh2po4, k2so4, equlibrium, csm+b, and iron chelate from gla, but I have learned to
care more about light and co2, as much as you hear that I am saying it again. It's easy to dial in your co2 at first, but
before you realize it your plants have double or tripled in mass and you keep thinking "my co2 is maxed out tho". But your
co2 demand has also doubled or tripled and all those annoying things you thought might be this deficiency or phosphate limited
gsa, blah blah........turns out to be co2 and you kick yourself square in the nuts!
Bottom line, might as well dose extra k and fe, but don't look for some magic cure in them. Light and co2 turn out to be the
culprit even when you can't imagine it.
Sorry for the ramble, and remember this is my humble experience only, I am not trying to be some expert or claiming this to be
gospel so take it for what it's worth to you