The dose is irrelevant. What are your test results? How long have you been dosing this much? It seems like a lot, but if your plants are happy, you are happy with your algae situation, and your nitrates are not hurting your fish, then I would say you are on the right track.
Dose(frequency X mass) is entirely relevant, it's the test that are not relevant
, that's the point of EI.
The main tenant actually.
The idea is that you avoid test kits, which also need another layer of confirmation by calibrating the test kits/method you are using.
Otherwise you are guessing or assuming that these Test kits, which many folks seem to hold dear and cherish as some shining beckon of truth, are in fact accurate and correct in their readings.
Perhaps 10% of folks in this hobby do this step and I'm being pretty generous.
EI is fairly straight forward on the other hand.
You guess some, but you also know most of the ppm's will be within a useful range that's acceptable based on risk and infinite series dilution math.
I think many assuem there's some risk involved with dosing ferts, perhaps too little I would say...but I've not met anyone or heard of any confirmed cases, and plenty of folks have messed their dosing up and added wayy too much quite often over the years, without ill effects.
Test kits have their own issues, they hardly solve an unknown unless you use them correctly. I suggest using high quality test kits, such as Lamottee or Hach, something I've stated and been on record suggesting to hobbyists since Steve convinced me back in 1996.
To the poster, you have a lot of light, should be okay if you have enough CO2, that will be the main issue. Good current helps, you lose a bit of CO2, but you add a tad more to compensate. But..you also gain good stable high O2, which the fish will thank you for.
A good trade off.
There are many calculators that use EI etc to help folks micromanage ppm's.
I really have not found they offer much advantage to hobbyists.
I think watching and dosing progressively slight less every 2 weeks till you see a negative response, then bump it back up to the next highest dosing works fine if you want to minimize fert ppm's.
No test are needed other than good observations.
Still, light and CO2, general plant density(you said it's very dense) play a much larger role than ferts.
Less light= less CO2 demand thus more wiggle room in adding this, and also less uptake demand and thus more wiggle room with nutrients as well.
Many.most hobbyists add too much light for what they would like to do growth and management wise.
With 260W of PC, you likely have 4x 65W.
You could run one bank of lights(130W) for 4-5 hours, then the rear bank for 4-5 hours, or have a little overlap where all are on for say 1-2 hours.
That would make things more manageable.
Dosing seems a bit rich to me.
I'd suggest 3x a week(you can subdivide to daily amounts if you wish, whatever gets the ferts in the tank)
3/4 tsp KNO3
1/4 tsp KH2PO4
Gh booster after water change only: 1.5 tsp
Traces: about 15ms or so.
I dose a bit richer or less depending and how the tank is doing.
Typical issues: not cleaning filters, not trimming plants, poor current due to plant overgrowth etc, poor CO2 etc, forgetful dosing.
Since you dose daily anyway, might as well add the macros into a liquid for a 2-4 week's supply and dose the mls. Keep the traces apart from the macro solutions, you can add them both to the tank at the same time etc, just do not make stock solution with traces/PO4 mixes.
sells the Fe gluconate, "generic Flourish Iron" now BTW.
I'd spend more time on light adjustments, reduction and good CO2 management. Nutrients should be VERY easy if that is done and growth excellent and manageable.