Nice jobe on the tank the video is good that it does show some week pealing wich is good. I had algae issues like yours and it took me a long time to figure out.
Basically you have a nutrient imballance. your tank is probably deficient in some nutrient. Your plants are growing well after the water change but growth slows or stops due to the deficient nutrient. Algae however is not affected by the deficiency and takes advantage of the nutrients the plants cannot use.
The problem starts with your water and substrate. Not all tap water is the same and some tap water has a lot of nutrients while other people have water with no nutrients in it. The substrate may or may not add any. Leaving your fertilizer as the major source of nutrients.
Farmers and gardeners typically pay close attention to NPK because they wash out of the soil easily when it rains. Most don't worry about all the others due to the fact they don't wash out easily and stay in the soil. Most fertilizers manufactures pay close attention to NPK because it washes out easily and less attention to everything else. manufactures also cut back on some nutrients that are common in tap water to reduce manufacturing costs.
So Lest start looking at your fettilizers. Your macro bottle Has NPK. Good But what about the other 4 macros? The macro list is N,K, Ca,Mg, P, S, Cl. Note I ordered this list on the rate of consumption by plants. Plants need a lot of nitrogen so that is first and while Cl the, least used macro, is last. Tap water is chlorinated so typically it is not a problem. Ca?, Most fertilizers don't have any. Mg? Most people think of this as a micro not a macro so it is in your micro bottle at a dose less than what plants need. And then there is sulfur. Were is it?
Ca Mg, S, and CL are typically found in tap water but not always in appropriate amounts. Many people use GH boosters to compensate for low Ca, Mg levels. A GH test will tell you the overall Ca and Mg level of your water but it will not tell you the level of each. Most of the frequently used GH boosters listed on this site are made from calcium sulfate and magnesium sulfate. Which would provide the Ca, Mg, and S plants need. Most tap water is chlorinated so that is generally not a problem.
Now lets look at your micros. The full micro list by order of consumption is Fe, Mn, B, Zn, Cu, Mo and Ni. Now fortunately this company list the PPM dose their fertilizer supplies. Based on ppm dose level Fe, Mn, and Mo are fine. but copper is a bit low but OK. Unfortunately the good news ends there. B and Zn are very low and Ni is not present.
Typically you want to see B and Zn at about 0.02ppm. Copper at 0.01ppm. Nickel is the least used of all nutrients and a dose of 0.001ppm is probably more than enough. Nickel is also one of the last nutrients identified. Basically the combination of fish waist and tap water is enough to supply nickel. Many water utilities use copper pipes or galvanized steel pipes so corrosion can sometimes provide too much but there is typically some in the water. Some fertilizers don't include copper to make them Shrimp safe. Yet from my own experience plants will not grow without copper in my RO/DI water tank. 0.010ppm of copper is safe for shrimp and some tap water has a lot of copper in it. My tap has 0.05ppm of copper in it.
When EI was developed the issues with Ca, Mg, S, were not known. only in about the last 5 years have people been paying more attention to these nutrients. Also When EI was developed the best micro mix on the market was used, CSM+B. Only recently the have people become aware of the problems in the micros. So some people including myself are now making our own micros.
At this point in time I would first focus on macros. IT is the easiest to fix and the most likely problem. Try increasing your GH to see if that helps. It is the easiest to fix. Many people aim for a gh of 4 to 6 degrees but it really depends on your water. Find out what your GH of your tap water is first and go from there.
As to your light,, Think of it as a car, the throttle is the light output, and the gas is your fertilizer. If you drive it at full throttle all the time you probably will run out of gas or something will break before you get to your destination. But if you drove slower thing will run better and you likely will not run out of gas.
Reducing light levels typically works because it slows plant growth and delays the onset of a nutrient deficiency in the aquarium. But if your nutrients are really out of balance it will not work. Tankfully your video is showing that your tank is running fairly well at he moment and the Algae issue is not as bad as I have had. So you are off to a good start. But you cannot figure out the problem you could use a lab test of your water. I have used this test:
It detects 13 of the 14 plant nutrients. it any one reads zero you are deficient in that nutrient.
As to TDS it will eventually stabilize if you are consistent with your water changes and fertilizer dosing. Yes EI does deliberately provide a little more nutrients than needed but it is preferable to do so . Having more than needed to make the sudden unexpected nutrient problems less likely to occur.
But like all equipment proper maintenance is needed to insure it works consistently. After use dip the sensor in distilled or DI water. This will wash off the minerals the water leaves behind. If minerals build up on the sensor the calibration will shift and the reading may increase.