I am disappointed to hear that scientist hobbyists have such a poor reputation on this forum. Hopefully I can help change that, although it does not seem I am off to a great start.
Instead of quoting everyone, i will just tag them otherwise this post will be far too long.
While I would agree there is no "exact" amount to dose a tank I am of the opinion there is a relatively fine range that if you go outside of, you will have issues. I think the correct range is highly dependent on how often you do water changes. I change water once every two or three weeks on most of my tanks and I think the fact that my schedule does not allow super consistent water changes means my range for error is that much smaller. If I were to do 50% weekly, that range would be quite large.
I completely agree that the 0.11ppm makes no difference on a regular schedule, but if you compound that error and let that 0.11ppm build for several weeks, IME you do eventually run into problems.
My point with seachem, or any large scale liquid supplier, is that their margin of error when weighing and mixing is much smaller because their scale is larger. I use graduated cylinders to measure out my liquid (seachem) which helps me ride that line of dosing without excess. In addition to the amount you would weigh out (assuming you aren't just using spoons), you also have the error in the amount of water you are dissolving it in. In short, a consistently premixed liquid simply allows me to be more precise than dry, which in turn helps me ride that line (or range).
Your point that the pump head is far less precise than either liquid or dry self mixing is well taken. So far it has worked for me, but the long term (several months +) effects are yet to be seen. The fact that the pump head variability has not caused problems is a testament to your previous point that there is no exact amount to achieve the desired results.
I suppose you are right EI can be done with any type of fertilizer, I have just only heard it in the context of dry ferts.
I think we probably just have different experiences based on how much water we are changing as well as plant load water volume ect...
I also did not believe that you couldn't mix macros and micros, but I did actually do my own tests and its a very interesting topic. if, for example, you dissolve your dry ferts directly into the aquarium and dose both on the same day, the water volume is so large aka the concentration is so low you probably will not see any precipitation. If you dissolve macros in one stock bottle and micros in another stock bottle and dose into your aquarium, the same is true: no visible precipitation. If however you try to mix your own AIO, dissolving micros and macros into the same stock bottle, you get a precipitate after ~1hr. I don't know exactly how much is lost and/or how much less effective it is, but the plants certainly cannot uptake the precipitate.
Yes, plants love phosphate. As I mentioned in a previous post a lot of times I add 1 mL of seachem PO4 depending on how much I am feeding. For that reason, I appreciate being able to control the PO4.
Lastly, I completely agree ferts do not make or break a tank and they are in a dynamic relationship with all the other elements, however, this thread was just about ferts.
@Sam the Slayer
You certainly could choose a different chelate. I have not noticed any pH swings by dosing EG. I am curious, have you?
I am only saying that I am trying out easy green as a base layer and supplementing as needed. The AIO idea exclusively is already out the window. I am just using easy green to cheaply get the majority of my ferts in the water and the fine tune the rest.
I did not mean to start any arguments about what dosing method or regimen is best. After all, as many have said on this thread, there is not a "right" way to dose a tank. As the title of the thread suggests, I was just trying to see if anyone else was using AIO's to make their personal dosing regimen easier. It seems as though many of you do, or at least have tried based on the number of people referencing EG and Thrive. Curious why no one has mentioned Dustin's Grow Juice?
I don't have time right now to do a whole tank journal thread but here is a sneak peak at some of my current projects. This is my 100G paludarium build. Its a tricky one because the dirt at the water line constantly adds organics to the water column. (trying to attach photos but it is not entirely intuitive as a forum newbie).
The little planters are an ongoing experiment of mine with dirted plant pots. I want a system for good growth that will allow me to sell root feeders to my LFS without them looking like crap in the store after a few days. Example: crypt melt
I feel like for my first thread here I should have chosen something less controversial than fert regimens, yet I find myself broaching the subject of dirted tanks...
Oh well, I have never been particularly good at making friends anyway