N:P RATIOS IN ESTIMATING NUTRIENT LIMITATION IN AQUATIC SYSTEMS

[SantaMonica]

Actually the abstract said that net photosynthesis increases up to a point, but decreases if flow increases further. This is common in flow studies.

[rleahaines]

An experiement to see what actually happens should be fairly easy to do with a waterfall scrubber or even a UAS.

run the scrubber with high flow for a while and then compare it to low flow

Athough I wonder if we could even get to a high flow state that actually decreases photosynthesis and algae growth at all in a scrubber set up.

From a practical standpoint, I could see that dwell time of water over a scrubber may have something to do with gas exchange and therefore growth, but I suspect that the actual growth would be more dependent on light, the kind of algae and multiple other factors once we have a certain flow rate.

[Floyd R Turbo]

There is a balance factor here as well. I have ran a scrubber with low flow (20 GPH/in) and got great growth, also good growth at even lower flow, but too low and your overall turnover rate is too low and you get algae growth in the tank. Too much flow seems to grow a little less bulky algae, it doesn't stay in the holes as well, and it grows much longer and sort of "slimier" but still green, and the very high flow rate seems to not outcompete tank algae any better than low-flow with very thick growth. This is why I upped the pump size in my units and included a inlet ball valve.