Turbo's Aquatics HF L4 scrubber

That's only the 2nd time I've seen this, the same thing happened to @Ricky about a year ago and we never figured it out. I thought it was photosaturation but to me that doesn't explain it, because it's such a sudden change. I get white algae on my top of tank UAS test unit when the algae gets thick enough to limit the flow, and then right on front of the LEDs it turns white, but you're getting is in a swath across the whole screen. So weird.

My gut tells me that maybe the scrubber is "doing it's job" and there was a drop out of some nutrient or amino acid or some kind of conpound in the tank to a certain point where that compound became a limiting factor, and this sudden change in water chemistry meant that the dominant strain of algae could no longer grow effectively - so it's getting a ton of light, but can't do anything with it, so it goes white quickly.

If this is the case, and it most certainly might not be because honestly that is just an educated guess, the only thing I can think of that might need to be done is to scrub off the white algae a little more than you normally would at this point (gently, with the small toothbrush) and see if that helps.

There also might be some chemical warfare going on between 2 algal strains that are trying to survive in a now-nutrient environment. If this is the case, then there isn't a whole lot you can do except let them battle it out. If this is the case (again, no idea) obviously one has lost the battle and needs to be removed from the field on a stretcher (scrub)

That's my take on it. But again, your guess is as good as mine.

I would give the whole screen a gentle scrub and then back the hours down by 2 hours/day

What is the condition of the tank?

Any algae?

Have you tested for N and P lately?

Alkalinity, Calcium, and Magnesium test results?

Do you have a Potassium test kit, or Potassium test results?

 

Well the only good thing is that we now have a second instance of the quick-white effect...

 

Still not sure what is going on with the scrubber, but you have a dinoflagellate outbreak in your tank, not algae. This is a bit typical in a new tank. Generally it's why you don't stock a new tank with lots or corals in the first 6 months - you're rolling the dice because there are a lot if "untestable" things going on in a reef tank in the first 6-12 months.

Dinos are toxic to most life so this is why your softies are closing up, which is definitely not normal

Run carbon and change it often. Reduce feeding, feed only at 15 minutes before lights out, run a filter sock, and suck as much of the dinos out with a airline hose daily. I would use a piece of hard airline about 12" long attached to the soft hose so that you can get right down into books and crannies. Then blow off all the rocks & corals with a power head and let the filter sock collect it (or use a very fine net). Rinse out the filter sock daily, an hours or so after your cleaning process.

This will probably need to be done for a few weeks and maybe 2x daily.

 

I was looking at it on my phone last night...now I see you are right, those are pods, you can see the little appendages!

I guess now that I can see these in higher res it looks more like very fine green hair algae instead of dinos. There does appear to be some air bubbles in one of the pics so the dinos might still be there. I would still make a thorough pass through the tank with an airline hose siphon and see what you get. The blow off the rocks and run a filter sock.

As for the scrubber, get me up to date:

What flow
What photoperiod
Have you change the jumpers on the LED boards at all

Bud

 

If the actual flow 500 GPH, or is that the pump rated flow?

How much are you currently feeding?

 

Hmmm...I think I may have missed this before, but then again, there was no issue with getting growth at first.

So your pump is rated for 500 GPH, but there is a head-loss factor. So your actual flow may be more in the 350 range, maybe 400, hard to say without knowing more info, but that should not be the major factor at this point.

Your feeding is rather low for a 4 cube/day scrubber. Initially, there might have been more in the water column for the algae to uptake: now there is not. This might explain the white algae - low nutrients, or something has become a limiting factor. A limiting factor is what occurs when a specific element or compound is reduced to the point where the algae simply cannot grow any more (or cannot absorb another nutrient, which is still in excess). But i have no idea what the limiting factor might be.

The result is that you have way too much light compared to the nutrients delivered to the screen (or possibly, too much light compared to what the algae has the limited ability to absorb).

So what I would do it split up the photoperiod and reduce total hours. Run it at 4 hours on, 4 hours off, 4 hours on, 12 off. Feeding stays the same, flow stays the same. Scrape the screen to get the white algae off. See what happens in a few days. If the white algae returns in about the same time frame as it did after the last time you cleaned it, reduce to 3 on, 5 off, 3 on, 12 off.

As for figuring out what the limiting factor is, that's kind of a guessing game if you don't have access to a lab to have your water tested, like Aquarium Water Testing over here (I'm guessing there is nothing like that in Serbia). If I had to guess: could be Iron or Potassium. @Ricky what were you doing again when this happened to you?

 

I'd say at 3 months you're pretty safe to put a couple tangs in. They will hopefully graze on the algae as well.

 

Thanks for the information. Yet another clue...but to what I still have no idea!!!

 

The connection would then be either N or P. Ricky was lowering it by carbon dosing, you by water changes. It doesn't have to be zero to be a limiting factor, but with N and P that usually is the case. Perhaps the connection is available nutrients. Concentration goes down due to carbon dosing or water changes, but scrubber settings remain the same. Once a certain point is hit, algae cannot be supported. Sounds like a good theory so far.