Excellent, thanks Partrobe!
So now we go to the lighting chart:
And find that a single T5HO bulb will produce about 80 PAR at 18" from the substrate. "PAR" is Photosynthetically Active Radiation, the amount of usable light your plants receive.
You have two bulbs, so we have to double that to 160 PAR. And since the reflectors don't look too efficient on that fixture, I'll be generous and knock off 20%, leaving you with 128 PAR.
That's already above
high light. And we haven't even added in the strip light or LED spots.
The more light you have, the more plants are stimulated to grow. The more they try to grow, the more nutrients they require. If those nutrients aren't available, the plants become unhealthy instead of growing. Like flogging a horse to run when it's starving, it doesn't end well.
High light tanks absolutely require
CO2. Excel provides carbon, like CO2, but it is not
actual CO2. The amount of carbon Excel can provide is limited, regardless of dosage, and insufficient for a high light tank.
High light tanks also require complete and heavy fertilization, to make sure all nutrients are present in at least adequate quantities, at all times. If even one nutrient is inadequate, things can go wrong in a matter of days. EI dosing is typically used for high light tanks, where all nutrients are added in excess
to make sure that none can become depleted. Then a 50% water change is done once a week to remove what wasn't used, to keep it from building up.
Successfully running a high light tank requires commitment and a bit of a learning curve.
And the more light you have, the more difficult it is to do. As you currently have more
than high light, it is unnecessarily
difficult. Even if you get your CO2 and fertilizers perfect, you're providing more light than plants can successfully use. The excess only causes problems.
If you are committed to running a high light tank, fulfilling the CO2 and nutrient requirements, and using your current fixture, then remove the strip and LED lights. See if you can mount your Solar Max fixture a few inches higher, so that you fall in the middle of the high light category according to the chart I linked. If that's not possible, you can mount one or more layers of window screening underneath it to block a bit of the light.