Clean the screen while dark

[Nick28]

Now since scrubbers use bicarbonate as a carbon source during light hours they are sucking it up and processing it. Perhaps cleaning the screen 15-30 minutes after dark will reverse this. As algae starts taking up oxygen instead?

anyone willing to test this over a few weeks and see if it saves their alk?

[SantaMonica]

Algae only does this if CO2 is low in the water, and still, usually only if the growth is very strong.

[Nick28]

Algae only does this if CO2 is low in the water, and still, usually only if the growth is very strong.

CO2 gas is always low in saltwater. Growth shouldn't matter as its only borrowed OH is released and bicarbonate reforms. If you remove heavy growth while its processing bicarbonate (under light) u should lose some otherwise u shouldn't lose any in the dark.

[Floyd R Turbo]

Low is a relative term. There may not need to be much CO2 in order for algae to grow and not take up bicarbonate. From a planted tank background, high water circulation/disturbance (reefs tanks, yes) tends to lower CO2 if CO2 is being supplemented. But in reef tanks the gas levels reach equilibrium with the ambient air, so again, low is relative to the need. Also the higher the bioload and thus respiration, the higher the dissolved CO2 will be.

But on the OT, the exact conditions at the exact moment at which you clean the algae screen should not make a difference, as this is only once per 7-14 days, and the removal of the large amount of growth removes the strong growth (+1 to what SM said)