This calls for "standard answer #42"::hihi: You can probably get more effect, cheaper, with far less algae problems, by working to improve the CO2 concentration in the water. Good CO2 means enough so the plants pearl a couple of hours max after the lights come on, and the fish aren't having problems with it. You may need better water circulation in the tank, to distribute CO2 rich water better, or just a higher bubble rate. If you use a drop checker you should be able to get the bubble rate up near where it needs to be, then make small increases, once per day, while carefully observing the fish for distress. And, if you make sure you have some surface rippling of the water, that will improve the oxygen absorbing of the water, allowing the fish to tolerate the CO2 better.