Tape as diffuser

You would connect as described in the manual, without using the splitters - connect the 2 fixtures in series (one male connector to the female on the other fixture) and connect the remaining connectors to the driver. This operates the fixtures at full current / high power mode

Using the splitters operates the 2 LED boards in parallel / low power mode - 50% of the current goes through one board, 50% through the other board (current divider)

You are operating at low power mode, and still getting yellow growth, so I would not switch over to high power mode.

 

What you're going for is results. Growth type is a close secondary. If you are only lightly loaded, yes I would cut back. I would not feed more just for the purpose of growing more algae in an attempt to get green hair algae.

If you are running an L2 and only feeding 1/2 cube/day, I would recommend 6 hours/day of lights at full power, or 10-12 hours/day at half power. I recommend the longer photoperiod at lower intensity. "lower" is kind of relative. Compared to CFL, the LEDs even at 1/2 power are more intense.

 

Are you sure it's cyano? Could it be dinoflagellates?

Post some pics, let's be sure.

 

I think that looks like cyano. Not sure what the white stuff is though.

I don't think that's a false reading, considering the algae growth you are getting on the scrubber. Pulling the Phos down from 0.37 on 8/24 to 0.02 on 12/4 and now zero, that's not out of the ordinary.

Cyano is one of those things that can also be a phase. Cyano has the ability to make it's own fuel to a certain extent, it extracts it from the surroundings, which is why it's one of those buggars to get rid of. Give it some time, and leave the scrubber right where it is.

Cyano and Dinos usually come after a change to the stability of the tank. Going fallow and then ramping up again can cause this, but it should go away on it's own eventually

You might have to emplore a daily routine to keep it from affecting your corals until it "burns out"; something like this;

1) blow off rocks/corals with power head daily
2) net anything you can that is floating around in the tank afterwards, using a brine shrimp net
3) siphon out everything you can. Use a piece of hard airline tubing (like for an undergravel filter) and connect soft airline tubing to it and use that as a "probe" to get to the cyano without putting your arm all the way into the tank. You can pinch off the hose when not siphoning. I was able to go over my 120g tank in 20 minutes only removing 1/2 gallon or so of water using this technique.
4) run a filter sock for a few hours after blowing off, then rinse it out and optionally put it back in (not required)
5) run purigen and/or carbon, and optionally GFO. These can be in a media bag in the flow path in the sump, you don't need a fancy reactor. Turn the bag(s) daily.
6) feed only the amount your fish can eat in 5 minutes, and do that towards the end of the daily light cycle if possible
7) don't do any significant water changes, cyano can actually be fueled by water changes. You have to let it "burn out"
8) I would not do a tank blackout unless it becomes a serious problem and threatens corals
9) I would not change the light cycle. Actually I did the opposite when I had dinos, I let it run longer, theory being that high light and low feeding would burn it out quicker, I don't know if it did, but it went away even though that went against all logic.

 

Great! Another case to support my theory

I see this question often, I don't know that you need to "dial back" the algae scrubber, or that LPS like "dirtier water".

I think the "dirtier water" thing stems from people keeping ULN / ultra-clean systems for SPS corals, which is now seeming to be a dying theory - people are more and more promoting nitrate above zero and phosphate above zero as well, an limiting carbon and iron instead for heavy SPS growth.

It's very likely that the "dirtier water" theory has nothing to do with what you think it does.

What I will say is this: early on, I was told by SM that I wouldn't be able to keep my pulsating Xenia with the scrubber because the scrubber would make the water "too clean". That was dead wrong, I had a Xenia explosion, as well as other soft corals, and I continue to have tons of splitting and heavy growth with things like fuzzy mushrooms and xenia and anthilia, etc. Simply not removing particulates means your water is dirtier. So instead of running, say, a filter sock 24/7, run it one day a week (after you blow off rocks or clean glass, etc).

What is more likely is that there is some kind of chemical allelopathy at play that is making your corals not open up. Running a very small amount of GAC and also GFO (like a few tablespoons) can mute these chemicals without "polishing" the water (these things don't remove particulates = food). Just drop a media bag in the sump in the path of water flow and turn it over often, and change it weekly - no reactor needed, unless you determine that you need to run it more aggressively in order to get corals to open up. Also this is a cheap way to test the allelopathy idea