# Algae limitations

I’m working on a water quality simulation and am trying to get my algae to grow (unsuccessfully at the moment). What are the limit outputs? From the manual:
LimP phosphorous
LimN nitrogen
LimNP nitrogen and phosphorous
LimL light
LimT temperature
LimA all

However, the thing I don’t see in the manual is a statement that 1 fully limiting or is a zero fully limiting? I would assume 0 is fully limiting but I would like to confirm that.

Thanks
Drew

Hi Drew, please refer to section 4.3.1 of the WQ Manual in the “Documents” folder of the set-up package. From this equation we see that as you said, algal growth depends on nutrient availability, ambient light and temperature. The effects of these processes are considered to be multiplicative:

Px = PMx · f1(N) · f2(I) · f3(T)

where:
PMx = maximum growth rate under optimal conditions for algal group x (day-1)
f1(N) = effect of suboptimal nutrient concentration (0 ≤ f1 ≤ 1)
f2(I) = effect of suboptimal light intensity (0 ≤ f2 ≤ 1)
f3(T) = effect of suboptimal temperature (0 ≤ f3 ≤ 1).

So 1 means no limiting. If one effect is zero then the net result is that everything will be zero.