Bio-chem Q: Algae scrubber and its causal effect on DT algae

[zalick]

@Randy Holmes-Farley - I've been wondering about the potential causal relationship between algae scrubbers in the sump and perceived reduction in DT algae. I know lots of people swear by the results.

All the water in the sump originates in the DT. The nutrients in the system, in general, originate in the DT. So any nutrients available to algae in a scrubber would be available to algae in the DT first or simultaneously. And in general, the available nutrients would be evenly distributed in the water column. Leaving light as the only true variable.

I'm struggling to understand from a chemistry/bio-chem perspective how a scrubber could "outcompete" algae in the DT. If there are available nutrients in the DT to feed the algae scrubber and the light in the DT is sufficient to grow algae, it seems like algae would grow there. Light is not a limiting factor. Sure, the optimal light in the scrubber might grow algae better but it's not like the algae in the DT would pass up the opportunity to grow.

From a chemistry perspective are my assumptions above correct?

Thanks!

 

[Randy Holmes-Farley Verified Community Expert]

The algae scrubber constantly lowers nutrients in that the water flowing back into the main tank is lower than the water leaving it, hence the main tank drops. It doesn’t really matter that the dt sees it “first”, the scrubber is keeping it lower. Neither uses it all in the first exposure. Probably not even a large fraction in each pass.
That’s the simple version.

 

[zalick]

Thanks Randy!