We have an analysis of multiple organic fertilizers, including Fish Emulsion, at 1/2x, 1x, 2.5x and 5x concentrations, originally found online. It gets messed up when we try to post it here and takes awhile to get it reorganized, so I'm not going to go through all that right now. The point is that if you look at the ppm of each nutrient under each concentration, the numbers don't go up linearly. The Fish Emulsion analysis, for example, lists ppm's at 34, 33, 35, 39 for Calcium at each of the four concentrations. Adding ten times the first concentration only increases the tested dissolved calcium content by about 14%. The 1x concentration even tested at less Calcium than when mixing half as much F.E. in the water. So how is this happening?
Take three coffee mugs full of exactly equal amounts of pure water and mix a TBS of salt in one and a TBS of sugar in another. Out of the three mugs, which will you now be able to dissolve the most extra salt in? The one that has only pure water. The fact that one of the other two has no salt in it is irrelevant to the question. The dissolved sugar will affect the amount of salt you can dissolve. The same thing also happens when mixing fertilizers. Even if you haven't yet put any Potassium in the tea you've been steeping Nitrogen and Phosphorus in all day, if you try to dissolve some K in what is currently a mud of other ferts, you won't get nearly as much to dissolve or get it to dissolve as quickly as if you had put it in pure water.
Some fertilizers dissolve very easily in water and don't require any more time than it takes to stir them to do so. The more easily a substance dissolves, the less other substances in the water will affect its dissolution. Because of this, growers should always start a nutrient mix by steeping the hardest to dissolve fertilizers first; the ones that take many hours to get all the good stuff out of like Guanos & Meals. Filter insolubles out next because if you wait until later, you'll lose some of the ferts you put in next when you do filter it. Now put in Maxicrop, any salts, soluble vitamins, pH adjusters; anything that doesn't need hours to steep. None of these last amendments should leave solids behind that need to be filtered out. Ferts that do that are only used in the first step.
