Well, I mean, Yeah. Adding more nutrients is the easiest thing to do in a planted tank. I really can't understand why it's such an issue. GSA is caused by any combination of poor CO2 and poor PO4. CO2 is the most difficult thing to fix, so, start with the easiest thing. Double or treble your PO4 dosing and monitor for a few weeks.
Here's my standard stock photo illustrating the point. This tank ran critically low on PO4 while I was out of town. No problem, I simply dumped a boatload of PO4 every couple of days and everything came good. What's the big deal?
If you add a massive amount and if that doesn't work then there is still no harm, and you'll know that the problem is either flow or CO2.
In this particular tank, the characteristics were that low CO2 triggered hair algae
before triggering GSA, so it becomes very easy to communicate with the tank. The plants talk to you, so you have to listen to them and learn their habits. Each tank exhibits it's own set of failure modes and health characteristics. Meditate on that and NOT on ppm, no matter how sophisticated the ppm reporting device.
Algae really does not harass me, because I have a clear vision of cause and effect.
Do not succumb to Matrix induced fantasies. Algae is caused by too much light and not enough nutrition. It can never be the opposite. Therefore, do not try to reverse reality. Algae will never cooperate with our personal hallucinations. Master the principles of causality.
Secrets of the Shaolin Temple:
Do not try to bend the spoon. That's impossible. Instead, only try to realize the truth. Then you will see that it is not the spoon that bends, but merely yourself.
Cheers,