Nick, whenever I have an issue I am attributing to a new additive I run a huge bag of carbon for a few days to suck it up, and do a big water change, as if I purposely ran chemiclean or something. That sucks though, I had a similar experience and thus hate additives. In the end, excess algae is from excess nutrients, and you can always export it - we are all just discussing how. I suppose with sand you get a little extra nutrients as it does trap detritus, and you have a higher bio-load from all the bristle worms and micro-fauna in the sand, but you can still export it. I agree with the DSB comment above, I dont see how it can be a filter if there is no water movement. Anyone with a DSB knows you do not want to go down beyond an inch. Every so often I scrap the front of the glass below the sand to make it clean looking for a party, and it bumps the alkalinity up very fast, like in-tank kalkwasser, and bumps of nitrate and phosphate. When I do do this I do a water change immediately after.
In general I have found that my small biopellet reactor and the occasional dose of vibrant reef, which is just a bacteria supplement, keeps it all perfect. Once every 18 months or so I may have a cyano outbreak and will use chemiclean. I attribute it to my T5s burning themselves to a different spectrum, but honestly it is probably just nutrient buildup over time and I would probably be fine doing a couple big water changes back to back, but chemiclean does work great for cyano (which is a bacteria not an algae). I have seen a lot of other cool gadgets popping up that I might try if my system wasnt already working well - dont fix what isnt broken. I especially like the idea of an algae scrubber, the concept makes a lot of sense - grow a **** load of algae on purpose out of sight to use up all the nutrients and starve the algae in the DT. Anyone had luck with one of those?