Hi. interesting post. My thoughts and experience (others may not agree LOL). I used to be quite anal about water flow. Added powerheads and messed with different flow rates. The result, algae still flourished. Now, this is how I run my tank.
1. Water flow is just moderate - fish food swirls slightly but not a whirlpool.
2. Water column doesn't turn into a tsunami
3. Put the diffuser near the outflow to push the CO2 bubbles around so that it has more time for the water to absorb the CO2
4. Focus on a more efficient way of diffusing CO2
5. Focus more on plant growth - ferts, lighting, pruning
6. Cleaning filter an a more frequent interval
7. Dosing ferts when plants are awake and not asleep
8. Clearing debris during water change
So, without worrying so much on water flow and not using powerheads, the results is much better for me. Plus, using ADA soil and ferts allowed me to get a head start in better plant growth, and enjoy a planted tank that is free from algae. Only occasionally algae pops up, but much more under control. Hope this helps.
