Sometimes people see lots of pictures of green-hair-algae packed scrubbers, and then worry when their own scrubber is only growing slime. Well, here is some good news: slime pulls out more nutrients from the water than GHA does! And this goes for dark, and especially black, colors of slime.

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Now this may sound the opposite of what you thought. But think about it: Scrubbers usually start off growing slime first. Why? Because nutrients in the water are usually higher when a scrubber is first installed on a "problem" tank. So, slime can handle larger amounts of nutrients at one time. This slime starts off first, coating the surfaces, and quickly pulling nutrients out of the water. If nutrients in the water are higher, the slime is darker, which is even more dense with nutrients. As nutrients in the water come down, the slime then grows less dark. Interestingly, the slime coating also prevents GHA from attaching. Slime is king! So why then does everyone get lots of GHA, if slime works so well?

Because slime can't hold on. Slime is all about holding nutrients; not holding onto surfaces. Holding onto surfaces requires growing cellulose root structures that can hold on better. Cellulose structures like the roots and branches of trees don't do any filtering of air, but hold on great! The leaves of course do all the filtering of the air. But leaves can't hold on to the ground, so the roots do that instead.

In algae, the softer structures like slime do the filtering, but can't hold on. So GHA evolved a more solid structure to be able to hang on. Bryopsis takes this even further with "roots" that dig into rocks to get nutrients from inside them. Even GHA has the ability to use enzymes to dissolve into silica rock as a way to anchor itself. But slime just has trouble holding on, because again, all it's structure is for absorbing nutrients, not for mechanical attachment.

Slime holds on best to rocky flat surfaces, like our Green Grabber rocky textures. Slime does not hold on that well to plastic screens like those used in waterfalls. So rocky texture scrubbers will pull nutrients out faster, and stay covered in slime longer, thus providing better filtering in high nutrient water.

But all slime washes away if not harvested soon enough, such as every 3 to 5 days. So to get the benefits of slime, especially black slime, harvest as soon as the surfaces are covered. This usually involves brushing under running tap water. This will pull nutrients out of the water so that GHA may subsequently attach and grow.

Slime is good.