Unfortunately I'm not experienced enough to say what would happen if you added more than the recommended dosage. Im interested as well though!
Here are the two articles I was reading before starting vodka dosing.
https://www.melevsreef.com/articles/dosing-vodka-why
http://reefkeeping.com/issues/2008-08/nftt/index.php
The guy in the first article has a similar size tank to yours, I think he said 280g. And it took about 7 months to see a drop. It seems like he did use some nitrate and phosphate removers during dosing. So maybe vodka, water changes and nitrate/phosphate removers would help. Although it could be risky if things drop too fast and too much.
The second is a guide with the standard dosing instructions. Near the bottom of the article it gives some examples of some adverse effects of to much carbon dosing. Sounds like some fish can be sensitive and you can get bacteria blooms.
Overall it dose kind of seem like do a dose, monitor and be ready to correct the tank if needed.
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