WOAH! Your plants are still going that strong with only nitrate and ammonia added?!
I add everything.
Not just KNO3, but Traces, PO4, GH etc..........
I tested the sediment for K+, Trace metals, NH4, NO3, PO4.
Nothing changed other than NH4(went from high to near zero), NO3 does not bind(which is why it's a drinking water problem) so it was not really present in large amounts either way.
After 18 months.
Like all wetland soils, Rice paddy soils, they are N limited generally speaking due to denitrification, PO4 does not have an atmospheric component. They add liquid NH3 to rice soils right before the flood and then they seed the fields via planes(In CA, USA). ADA As is similar to the rice paddy soil here in the Central Sacramento River valley.
If you did not dose anything or very little, then the life time for Nitrogen would drop to maybe 6-12 months? I'm not sure, I did not take subsamples over time for 18 months etc.
So this would suggest the best case scenario, but also the wisest. You never run out and always have a back up, except for N after say 1-2 years.
Some assume that low/absent water column nutrients somehow is a cure for algae or grows plants better, is preferred, but there is no evidence for this, there are a large no# of aquarist who WANT to believe that is true. A good myth is hard to kill.