Dosing chemicals which you buy in dry form means that you know exactly what you are getting and can mix fresh solutions of different strengths when needed. Not only is it highly cost effective, but it also leads one to learn a little about the individual properties and their effects on plants and water quality. Buying ready mixed is convenient, but more expensive and you have less control. Currently, I buy Sodium phosphate and Potassium Nitrate. The mix I buy is Tropica Master Grow. My experience of using Seachem ready mixes has not been very good (neither has it been especially bad - expect for the Flourish Nitrogen which I do not like at all).
While Flourish is a good line for micros and such, I've heard people say that you have to add a whole lot of the Flourish Potassium and Flourish Nitrogen to get these to desired levels. It's cheaper to get some KNO3 and make your own stock solution.
That said, I do use Flourish Phosphorus, but only because I'm too embarassed to walk into a store and purchase Fleet enema :lol: . No complaints about the product...
If you scroll down to the "guaranteed analysis," it says derived from potassium nitrate and urea. I think plants generally have an easier time taking up nitrogen in urea form, but I believe this is the component in Jobe's fertilizer spikes that causes green water. All else being equal, I prefer straight KNO3 - make the plants work a little for their "food" and leave out any stuff that might not be good for the critters in my tanks.
Sorry if I misinterpret your question. Nitrogen (as an element) doesn't change its oxidation state the way iron does; it's bio-availability (is this an actual word?) is not dependent on the same factors that affect that of iron. In fact, nitrogen-based compounds are often chelatORS via the electron-pair on the nitrogen (something I vaguely remember from inorganic chemistry). So while chelation of iron (hence oxidation state) is critical in how plants use it, it's of little or no consequence in the uptake of nitrogen, AFAIK.
I mean, if you can actually get the Flourish Nitrogen for really cheap, I don't see any reason why you *shouldn't* use it. But I don't see how a 16-oz bottle of the stuff could be more cost-efficient than the same amount of dry stump remover. If you can, maybe try a side-by-side comparison between a tank using the Flourish Nitrogen (dosed as recommended) and another with similar conditions (and plants) using stump remover. I would be interested in the final results...
Hey, Greg! Wow - those are probably the best prices I've seen :shock: . Thanks! I'm definitely bookmarking the site.
Shane, I looked up the Flourish Phosphorus on the SeaChem site, and at the bottom, it said "derived from potassium phosphate." So like I said, it's going to be *way* cheaper to buy dry KH2PO4. Heck, even Fleet enema might be less money down the toilet (... so to speak ) because it's highly concentrated. Since my tanks are so tiny, cost isn't so much an issue; you're working with several large tanks, and it would probably be in your best interest to go the frugal route.
P.S. - BTW Greg, that Elatine triandra is doing great. I think it likes colder water. Even the pieces I left floating have been holding their own and continuing to put out new, healthy growth.
Flourish Nitrogen was indeed repeatedly the reason for an outbreak of greenwater in our soft New York water... The most useful thing that came out of that purchase was the plastic pipette - and I have now found a very good supply of those things anyway...