<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> Should we talk about it here or on APC?
All the same to me
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> With "just in time" fertilization you can do smaller less frequent water changes. Frequent large water changes are part of the estimative index. In that method they function as a flush'n fill reset of parameters. When you are more skilled and can maintain parameters such large water changes are perhaps, wasteful. I am observing slowed growth at about 12 to 16 days and do a 20% water change when I notice this slow down. In my case, the slowdown may be related to hardness nutrients since I only add dGH macros with water changes.
Your ratios seem about right, you might try more fertilizer each day and see what happens over several weeks. Since you seem to be using a test kit, increase amounts until residual N starts to be detectable and try to hold that state. With "just in time" fertilization, you want the point where your plants use most but not all of your supplementation. Feeding and gardening changes will also influence this state. You will need to adjust supplementation to compensate for those changes also. As you come closer to the sweet spot of supplementation you might then fine tune nutrient ratios for desired plant appearance.
It may be just superstition, but I alternate micro and macro ferts to keep P from binding to Fe. You might consider an every other day routine. And, as Tom suggests, always make sure CO2 is attended to before and after fertilization changes.
For comparison, imputing my current weekly totals into fertilator (daily amounts times 3.5, since I alternate micros and macros) yeilds 29.63ppm N, 3.58ppm P, 22.42ppm K and .28 ppm Fe, in a 190w/60g tank. These numbers do assume fertilator calculates correctly... sorry, I'm just too lazy to calculate on paper.
I think each method is geared for the different level of hobbyist. I think the estimated index is aimed at the new person in the hobby and is good because you don't have to test and understand a lot of what is going on.