I'll ask a simple question: how does a plant grow?
Nutrients alone?
Clearly not.
Light comes to mind as the first requirement.
CO2 is next but only suggest 30ppm.
This too is not correct.
While at HIGH light, 30ppm CO2 will saturate some plant species, at lower light, say 80 micro moles, the demand might only be at 15 ppm or less.
The problem with most discussions about nutrients are where the nutrients are located(sediment, fish waste, water column) and the other factors, such as CO2 gas addition and how much light you have.
Common sense goes right out the door.
EI works best for high light and very dense planting is not true. EI can and does work fine at low light, at less than dense plantings. You obviously do not need to add so much for tanks, it's likely wasteful, you know the plants are not using that much nutrients but you still dose the same amount simply because "so and so" said so?
Nope.
If you have a nutrient rich sediment, say ADA aqua soil, do you still need full EI? No, you can reduce the macros by say 1/2 and still maintain the traces. Sediments supply another source, so the full demand on the water column will be less.
I suggest for a low light tank, say 80 micro mol, 10-12 hour day, about 1/3 EI, and about weekly water change every 2-3 weeks.
Likewise, some folks like water changes 2x a week say 20% vs 50% once a week, you can do 80% every two weeks etc, you just need to figure how much possible build up is there.
You can tweak the dosing using some good test kits also if you chose.
But folks have lots of trouble using test kits correctly and are often too cheap(Rarely buy the Lamotte or high quality equipment) and forgetful to use them well over time.
With good reason too.
"Not using test kits" is a huge a selling point for the method if you can do weekly 50% water changes, and never build up beyond the 2x max weekly dosage.
Some add EI without any modification, some think you must do 50% water changes weekly, some add it on non CO2 tanks, some have hardly any light and think they are not adding enough KNO3 when doing full EI.
Folks have trouble measuring CO2 well.
Folks do not even measure light.
It's just a concept to dose non limiting nutrients and do water changes to reduce the build up.
Not much more than that.
You start at a high known non limiting amount, then reduce it down from there slowly and progressively till you hit a sour effect with the plants, and then bump it back up to the next highest level.
The actual amounts suggested do not cause algae at high light levels(and therefore cannot induce algae at any other lesser values as well) in and of themselves, this is true no matter how bad folks want to claim otherwise(and many still cannot get this out of their heads).
So that leaves CO2 and light as the main controlling issues for growth.
Using GH booster is my general suggestion for Ca,Mg, and K+ added extras.
They do no harm when adding a bit extra to supplement just in case you are low, basically going back to the idea of non limiting nutrients.
You can easily provide non limiting amounts of nutrients, then focus on what really matters, good CO2 dosing/light without interference from the nutrients.
Light and CO2 are much more difficult to address.
But should never be left from the discussion.
We should look at the whole process of plant growth and development, not just the nutrients. No method will work without giving due consideration to CO2 and light. I'd say that light and CO2 trend to be far more important over all, but most aquarist fiddle a lot more with nutrients.
Folks do not read it even if you write though
Thanks for the write up
Regards,
Tom Barr