Measuring dry weight biomass over time vs a O2 levels are different measures.
Both integrate many factors in growth.
For example some plants high produce high O2 levels while others do not but still produce lots of biomass.
How might that occur?
Think about that for awhile, think about plants that send most of their energy to the root zone.
If you are able to limit something like say KNO3 dosing,but still use K2SO4 and you had everything else in a non limiting concentration............ then it would show pretty well.
Otherwise it'll mainly be general growth/production parameter. You can tease apart some relationships with statistics in natural systems, but sometimes these are not really significant at that level.
The same might be true for plants unless under strong limitations, which generally do not occur in planted tanks for long without some other issue also appearing, folks might do it, but often it's accidental, not purposeful. Fish waste adds a fair amount to prevent such strong limitations for N and P, but not always, a number of folks have strong cases of each.
DO should correlate, I'm not sure how well and you are also going to need to integrate a DO level that rises and falls through time as well, that will change.
The fish load and rotting plant biomass from pruning will also cause issues.
Different plants/species respire and use more/less O2 as well.
Differential photorespiration abilities also vary and will influence things, Hydrilla is excellent for this reason as well as method of CO2 sequestration.
But to compare how well a system is doing in general, especially if pearling is your interest or gas, then DO is excellent.
But teasing it apart into the individual parts takes some doing and care but cane be done.
Regards,
Tom Barr
