vahegan's UAS test

[Floyd R Turbo]

I feel this is because

1) LED intensity will overpower growth initially for a certain period of time. Until you get a deep base formed, your growth will not bounce back from cleaning.

2) plastic canvas, while idea for waterfall screens, is not ideal for submerged UAS use. I'm going to go out on a limb here and say that it just takes time for the algae to root into the actual material on a UAS, then when it does, it can absorb the incoming light better and grow faster after cleaning. My screen has become progressively more 'stained' green, and this appears to not be so much staining as it is impregnation of the screen with algae spores. So after about a year roughly, it seems that the screen might hit a turnover point where growth can easily bounce back under high intensity LED light.

The difference with the waterfall screen is that the algae can form a mat in the holes and for some reason will hold on better in there, and the growth bounces back from that base and not so much the actual screen material itself. I have to scrape my waterfall screen hard. I barely have to scrape my UAS screen, even after 1.5 years of running it - most of it comes off just by grabbing it.

[vahegan]

What I find interesting - in the past months, it WAS growing algae (and yes, the holes between the net were even filled up better than now) but it was just different type of algae. Indeed, it required much effort to scrape off the screen. And yes, the screen was stained with unremovable algae from the start - actually, it was growing algae on both sides at that time.

Whereas the new type of algae is easily removed by one simple movement of the hand - if I scrape and wash after that, I do this only to remove any parts and bits remaining, so that they don't go back into the tank. Requires a very light, superficial effort - no hard scraping needed. The stain algae is still there on the screen, of course, but it doesn't produce much matter.

I suspect, maybe it took the "2D algae" a year to pull out some type of nutrients that were accumulated in the tank, and now the nutrient supply is changed to the type which is best utilized by the 3D variety?

[SantaMonica]

Yes, high nutrients grow dark, which block light. Low nutrients grow light, allowing 3D.

[Floyd R Turbo]

Vahegan, so define the type of growth you had in each of the 2 instances

In the past, firmly attached algae was:

Now, the less strongly attached algae is: