Up until now, I've avoided use of Excel since I can't get it locally, and mail ordering costs a lot in shipping. But now that I'm going to start a saltwater tank, the cheapest way for me to get salt is to mail order it. So the additional cost that it would incur to buy Excel at the same time would be somewhat negligible. My 30g tank has diy co2, but it fluctuates a lot (between 10 - 30ppm); and more recently I've had repeated outbreaks of brush algae and I know this is why. Will adding Excel to this tank help solve this problem, even if the diy co2 continues to be somewhat sporadic? If I decided to stop dosing Excel, would I see any withdrawal issues such as when you stop injecting co2? Any other drawbacks to using Excel?