I just found the nitrate reading curious and wondered if I should increase the amount.
Well, you can increase the KNO3 dosing if you wish.....it will not hurt, this assumes the test kit and the method and claibration are done and are correct, otherwise the NO3 ppm is a guess pretty much.
and the entire basis for doing anything different or not has some serious issues........
On the water changes, I set up an auto water change system using RO water exchanging from a compartment in my sump. That compartment holds about 12 gallons, and I can pump an additional 2 or 3 into it from a return compartment as well. Also, I have a limited reservoir of RO water, due to space considerations, etc. My plan is to keep Angels and other soft water fish so don't want to use my tap, which is well water and VERY hard. TDS of more than 500 from the tap. The water changes are a function of labor savings, because I travel a lot, the tank is very high, and I needed a way to allow my wife to do changes when I am away without dragging buckets into the living room and up a ladder, thus the pump driven water change setup.
Easy enough, you already have all the tools in place.
Consider 2-3x a week for 12 gal each time water changes instead.
You can even do it daily if you wanted and this will give nice results.
I've seen some awesome tanks done this way and without hardly any issues.
I've got breeding gold angles and Altums in tanks with 350-500 TDS........what specific type of hardness is critical(GH can be high, the KH needs to be lower however). A client has discus breeding in community tanks at those same TDS readings......
Nothing is going to build up with increased frequency.
Nor run out.
So then it's just an issue of CO2,m and perhaps running the light lower.......particularly when you leave for work/vacation etc for a week or a few days etc.
Run the light a bit more when you are around, less when you are not.
Use that as the throttle, seems easiest given your set up and concerns here.
Any suggestions on the lighting and period I am currently using?
My hope is to keep healthy plants without immense high maintenance growth......and of course controlling algae.
I suppose as suggested above........run the high light for 2-3 hours when you are around to do the work, and perhaps 1 hour or not at all when you leave, if you can raise the light, then that's easier also.
At 1.5 W/gal of T5 lighting, 2x a week is plenty of dosing for most systems.
If you want ot make the dosing issue easier, and have more flexibility, then ADA AS works very nicely and supplies nutrients if the water column is lean.
So when you are thinking about it, or around, the water column dosing helps, and extends the life of the sediment, and if you forget or leave for a few days, the sediment supplies nutrients.
Few folks have any real issues with nutrients and algae, unless they run too low etc for plants, it's mostly a CO2 issue. That's the biggest issue and why most every method, along with light can cause bad algae issues.
Too much light and poor CO2. Nutrients tend to be much more flexible.
Below is a larger issue and misconception perhaps
See Liebig's law on the Minimum and critical concentrations. These define growth and patterns of growth in plants.
Ratios I think are hold overs from folks thinking they outwit algae via ratios, not from simply giving enough nutrients, a decent light level they could manage and good CO2 levels. Too much importance given to one area and not the other two..........
Some use them as guide to add a certain amount, but......every tank is different etc, so to get around that, simply chose a high non limiting level that satisfies any
tank, then slowly reduce from there to target just enough via watching the plants. That nails every tank's unique amount, but adding more does no harm either.
That's the part that gets folks.
This is not a "new" idea, Farmers, commercial growers, landscape management all do the same thing
KNO3 cost a fair amount for 10,000 hectares, but it's peanuts or less for a 100 Gal tank. So they have more reason to measure it.
So have you calibrated the test kit you used over the range of interest?
It's hard and very hard at the lower ranges to tell the difference with the colors for NO3 and most PO4 test kits.
I target 20ppm pretty much. This is the critical concentration that provides non limiting nutrients for most aquatic weeds, see Gerloff 1966 for the reference. You have a 40% reduction at 10ppm and 60% or more reduction in the rates of growth at 5ppm according to Gerloff.
This is independent of other factors...........and the light was not that intense really.