Yes, now I think people say Phosguard can leach aluminum so people say to avoid it (I think Randy found that out) GFO is basically the same thing. The tricky part with GFO is lets say you load up the system with GFO you could accidently drop the system to 0 phosphates. If you get a 5 Micron mesh filter sock and use Phosphate E or Lanthian chloride since its a drop and works fast. You will see a drop in 24 hours while GFO/Phosguard takes days, weeks, or months and with GFO my phosphates were increasing after doing 4x the recommended dose for some reason lol. GFO is honestly better once its already stable but if I had another GHA outbreak I would start with manual removal since most CUC wont get it if its too long, use Lanthiam chloride safely until you see a meaningful drop. Reduce feedings & then add some Rowaphos or some type of GFO to keep it stable. A fuge helps a lot I hear too.
Also large water changes are not great at combating phosphates because of leaching from the rocks & breakdown of GHA etc. Also usually it does not make a large enough meaningful difference in the number.
