water, you'll never be fully rid of algae. I run all kinds of media on my tank and am stuck using distilled water you can get at walmart for 88 cents. I go back and forth on if I prefer GFO
or phosguard and recently started using biopellets to lower the nitrates.
With that said, your actual mechanical filtration will also be key, along with flow through the system. I would be MUCH better off today if there hadn't been a dead zone in the middle of my tank behind my rock work. It is something I have just discovered in the last several months...but it would be years of build up. Filter socks to pull gunk like this out of the water column without letting it settle is key to preventing things from going badly and turning into an 'old tank syndrome' crash scenario.