Yes, that is correct. It would be a complete waste of time/money to buy digi scales just for this purpose, however, if you like to measure accurately to the nearest 1/100th gram, and if it makes you feel good, then by all means do so.
I am currently dosing KH2PO4, KNO3 + Trace. I read that we should dose Magnesium Sulphate if Magnesium is at a low level in tap water but what is considered a low level? Current level in my supply is 10.0mg/l so would my plants benefit from adding Magnesium?
Low level is zero such as found in RO water. Mg is a micronutrient, which means you only need micro amounts. That means 10ppm is plenty and if you have that much in the tap then you won't need to spend any more money. It's always worthwhile though to experiment a bit by adding a few teaspoons to the tank at water change for a couple of weeks, and then see if it makes a difference in growth/appearance. If no difference is noted then just delete the addition and carry on. Epsom's Salts is certainly cheap enough and whatever you don't use in the tank you can use to soak your tired feet in at night.
On the far left is the hooligan stem Pogostemon Stellata and adjacent, to the right, is the red Alternanthera reineckii 'Purple' (lilacina). Then continuing to the right are two large groves of Limnophilia aromatica separated by an sword of unknown origin (I think it was sold as Kleiner bar). Just to the left of that sword is a pale pink/orange Ammania senegalensis. Of course, on the far right is just you run-o-the-mill Microsorum fern.
Most people don't like to do water changes (I hate water changing because it's boring). So that's why we normally only talk about doing it once weekly. But there is no problem doing 2 or 3 times per week, and I believe this is mucho mejor for the tank than doing it only once per week. Ther are two options:
1. When you change the water just add more NPK immediately and then add trace element a few hours later (or the next day). It doesn't matter what day you do the change.
2. Increase your regular dosing so that the concentrations are higher in the beginning. That way, when you do the water change, you will only be removing the excess. So for example, if you know that you will do 20% water changes 2 or 3 times per week then just increase your dosing procedure by 20%. Again, it doesn't matter what day. If you changed the water on a trace element day then dose the trace element at the higher value and don't worry about NPK because you would have dosed the extra 20% NPK the previous day.
the idea of EI is to provide an excess of nutrients so there is never as shortfall, so why dont we add every possible fert as standard to ensure in any instance all bases are covered? There has been discussion about adding Mg and Ca to the mix, are these not included as standard as normally there is never a shortfall? I can see the cost implications if theyre not necessary, but they could be necessary for some.
Hypothetically if using RO water with no nutrient content, and we wanted to provide everything our plants could possibly need fert wise, what would that list include, are there more fertilisers than is suggested in the initial dosing regime?
Because every other possible fert is nowhere near as important as NPK. There are lots of other elements that are completely ignored by EI dosing schema. We do not address Sulfur, for example, or Cloride, or Nickel. At the end of the day this particular dosing scheme was developed in order to be easy and accessible, and to cover the most important nutrients that plants require for optimal health. Calcium and Magnesium were considered adjuncts and are normally available in sufficient quantities just as are S, Cl-, Ni and other, more obscure micronutrients. Deficiencies in these are never as problematic as are deficiencies in NPK and Fe.
You need to step back and think about the context under which Barr developed this dosing scheme. At the time, NO3/PO4 were boogiemen, and people continued to suffer great difficulties with plant health because of their refusal to recognize or acknowledge plants' dire need of these essential components. EI dosing addresses these basic needs and resolves the issues associated with poor performance. Only very rarely do we ever see a Calcium or Sulfur deficiency, for example, so really, , this was not really a focus of the dosing scheme, although, yes, this can possibly occur if using RO water without remineralizing it, which is not a wise thing to do anyway.
Therefore, if you are using RO water it should definitely be remineralized, either with tap, with GH Booster, or with one of the (more expensive) commercial remineralizers. EI does not really want to be responsible for fixing this basic flaw in plant and animal husbandry.
Assuming you have followed the remineralizing procedure, you can now follow the basic EI dosing scheme. Adding more of everything can certainly boost performance, can enhance colors, boost growth rates and can even stimulate flowering in some species, but these special enhancements are not the objective of EI. The objective is to fix the most important and basic needs of plants. This doesn't mean that we avoid suggesting to add these adjuncts, quite the contrary, but these are less important than getting people to realize that they should, first and foremost, always address Nitrogen Phosphorous and Potassium in their dosing program. NPK are 1000X more vital than Calcium.or Magnesium or any other micronutrient we can think of.
Thanks for clearing that up Clive.
The RO water was hypothetical of course, i use tap water myself. Im new to EI salts and am just trying to gain a more complete understanding. NPK and micro are the way to go then. I just wanted to see if there was a way of providing everything so as to 'entirely' rule out fertiliser deficiencies over for example C02 issues (which i know yourself and Tom Barr suggest are nearly always the reasons for poor plant growth). Im currently having some issues but thats for another sub forum!