Photo inhibition (too much light)

Many new users of strong lights on new scrubbers try to start out with full power light, thinking that the reason they got the strong lights in the first place was because there is a nutrient/algae problem and it requires strong scrubber light. Only to find no growth at all in the scrubber.

The reason is photoinhibition, which means "inhibited by illumination". Algae can only grow in light (illumination) up to a certain brightness; above that, it can't grow. So what is happening is that the user tried to use full (high) illumination too soon, and the algae could not get started. So, the solution is to reduce illumination until some color of growth begins which then will absorb the light.

This applies to all algae scrubbers, but especially to SMF scrubbers which have very strong PAR lighting. Weak lighting, such as on non-SMF scrubbers, will sometimes seem to start growing sooner because the weaker lighting is not too much for the algae. But with SMF scrubbers you are recommended to reducing lighting to begin with, and this sometimes takes a few adjustments. The super bright white Green Grabber surfaces of SMF scrubbers further reflect more light back to the growth, enhancing the illumination.

Why provide such strong lighting (and reflective white surfaces) which you just have to reduce when starting out? Penetration. Once the scrubber gets past the initial thin layer of growth, the light will need to be strong to reach the deeper layers of algae, or else the deeper parts that are holding on to the growth surface will die and let go. If they let go, you lose your filter. So SMF lights can then be increased to take care of this. And the white reflective surfaces further help illuminate the deep areas more, because these are the surfaces that the growth is attaching to.

Dark/black slime growth also needs stronger lighting because the darker color blocks more light. Non-SMF scrubbers will often stay in the dark slime stage, because the lights are not strong enough to penetrate and grow a lighter color.

So use the included illumination reducing techniques with the SMF scrubbers (shade screens or cloth) to start out. Once any color of growth covers the growth surfaces, remove the shade.