Cyano on the screen?

[Vannpytt]

One week after adding another light and increasing the flow. It's really stuck on there, looks like some short moss, spungy, yellowgreenish, or light light brown. Greener at some spots than others. Adjustments?

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[SantaMonica]

If you can't increase flow, more, then try adding iron, like Kent's Iron + Manganese. This will help it grow greener and longer. Last resort is to move the light further away, or decrease the light hours.

[Vannpytt]

i'm one of those anoying people who wants to know why. I'm reagarding this thread as my "building blogg" for my own reference when I set up a scrubber for my new 240gallon later this summer. I really appreciate your feedback tho. I can increase flow, quite radically, but I need to know how much and also wich to know why. If adding Iron is best option, I'll do that, if increasing flow is, i'll do that.

[SantaMonica]

Yellow mean it's not getting enough nutrients like iron. Increasing flow delivers more iron, as well and nitrate and phosphate. But if the algae gets washed away, it doesn't help. So you manually add iron. A very rough screen is what is needed. If you see bald spot from day to day, the algae is letting go.

[Vannpytt]

No bald spots, but the flow is so strong from my 20cm wide slot that it looks like a sprinkler system even with two layers. I could probably widen it even more, but then it's not alot of pipe left It really is rushing down there, the screens are very rought, did it so much that the plastic mesh almost scredded. Guess I'll have to dose iron to grow the algae. I'm using Hobby Ferrogan 24. It's some highly concentrated product. Hope it doesn't kill anything in there. How soon would I see results from adding it, and would I keep doing it even after gettign green?

[SantaMonica]

Well I'm sure that stuff has iron, but I'm not sure about the other ingredients for a reef. If you put enough iron, the yellow will starting turning green in one day.

[Vannpytt]

Measured nitrates today. Not measurable for the first time since I added fish 6 months ago. I got a decent bioload, feed 4-5 times a day and don't change water or use a skimmer. I'm not even growing greens on my screen, altho the iron seems to help.

[rygh]

It now looks a bit like mine did.
Especially if it is fairly solid lumpy ice-plant like yellow, not a dusting.
What fixed it for me was reducing the lighting. Changed period down to 12 hours, and added some tape to filter it.

Interestingly, I am not convinced the color matters as far as filtering, but it does save energy, and the green
seems easier to clean off.

[Vannpytt]

following the logic, more light=more filtration.

I spoke to a local biologist who said plants are very dependant on iron, not a very common addition to a saltwater aquarium, but it seems to help. its alot darker today already. Even too dark, but very much greener. The growth is good in general also, and no nitrates anymore. used to have 20-50 on my RSM tester

[SantaMonica]

The green vs. yellow makes a difference when you can get green hairs. The hairs, spaghetti, or other stringy algae filter the best (because they let light and water flow all around them), but they don't come in yellow. Yellow always stays packed tightly, blocking flow from getting to the bottom layers.