Growth Rings

Growth Rings

The usefulness of "growth rings" (which are sometimes called bald spots) was not fully understood until recently, and in the past were avoided. But it turns out they can be a beneficial tool especially for waterfall scrubbers.

Growth rings have algae growth on the outside of the ring, and some possible lighter growth on the ring itself, and no growth (just white surface) inside the ring. This gives the advantage of self-adjusting growth ring size based on nutrients in the water because the inside of the ring can handle higher nutrients (because of the stronger light) when the outside of the ring might grow dark slime. And indeed a common time to get growth rings is in high nutrient water when the scrubber is fairly new.

Also, since waterfall scrubbers mat down with new growth on top of old growth, the growth can get too thick in the middle and cause a dead spot in the middle of larger screens. This dead spot looks like hay (light brown) and can also be slimy, and this dead growth commonly lets go and falls down and clogs the drain. Even if it does not let go, you will still see the light brown spot when you harvest, and will notice the growth it not attached at all. This hay colored (and sometimes slimy) growth is what can cause the water to turn yellow. So, by keeping the middle of thick growing screens more "open" by having a growth ring, you allow water and light to reach this area to keep it alive longer and thus avoid any water yellowing or drain clogging.

The LED lamps in Santa Monica scrubbers (such as the GEM5 lights on our RAIN scrubbers, and the sealed LEDs in our DROP scrubbers) are strong enough to create "growth rings" on the algae attachment surface (screen or rocks). The white surfaces inside the ring (especially on DROPs) also provide for more reflection of light back to the dark growth areas.

Here are some examples:

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Interesting to see this. Maybe I needn't have tried to move my lights away from the screen after all.

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Ring !

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Here is an almost perfect growth ring, allowing full flow to the thicker inner parts of the screen:

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This type of slime growth on this RAIN4 waterfall scrubber in saltwater really needs the screen, tray, and pipe slot to be brushed clean every 3 or 4 days, and would do best with an optional Slime Screen so the slime can reallly hang on. More light is not the answer, as you can see, because the light is strong enough to make a growth ring, which is about as strong a light as you can get. More info:

http://algaescrubber.net/forums/show...3-Growth-Rings
http://algaescrubber.net/forums/show...he-best-filter
https://www.santa-monica.cc/cdn-cgi/...es%20front.jpg

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