Scrubber build

Regarding your lighting: yes, time to increase hours. Your base growth is not slime, so you can safely add hours (go to 12-14) and could probably add intensity also, but I’m not sure what level of control you have. If only diffusers, leave them in for a few more weeks

 

Also your refugium and scrubber are competing with each other. Refugium needs constant pruning to be effective, like 25% removal several times/week or else shading effects reduce effectiveness. So I would do a 50% pruning now and let the scrubber get a stronger foothold

 

In my experience the best growth happens in a system with a good diversity of life. So if you're only dumping skimmate into the system, that could be limiting the source of nutrients to a limited subset.

Urea excreted from animals is probably the best source, ammonia being the primary substance. That gets taken up pretty quickly by bacteria in the system, so it's probably not very high in the skimmate (just a guess). The point being, while logic might lead one to think that skimmate would be a good source for algae to grow from, it actually might not be.

I wouldn't put a nail in the coffin yet. I think you should have left the scrubber connected to the tank and pruned back the fuge. There are many factors that go into why a scrubber may not be producing as expected.

 

Looks like it should be OK. If the screen is pretty much bare, you might consider connecting those 2 arrays in parallel so that you get 350mA in each string for a while, that might avoid any photosaturation issues

 

Yes, that would probably work OK as a diffuser. You can also get diffuser material from Lowes or Home Depot in the section where they stock the lay-in ceiling tile. It's brittle so you have to be careful when cutting it, I prefer to score multiple times and then snap, but wear eye protection because it literally can shatter. I actually used to cut it on a table saw, again very carefully (it really shatters when it goes when ripping it on a table saw)

 

Now I see from your signature that you're from the Netherlands (?) so I doubt they have Home Depot there but any home improvement store that carries the 2' x 4' grid ceiling tile should carry this diffuser material

 

Actually a standard-use blade works better on that plastic stuff. The high teeth count blades and plastic blades just melt it. If you're looking at only needing a couple small pieces, just cut with a razor knife. Lay it down with the bumpy side down on top of a towel (an old one). Then use a straightedge or level to make your scoring line, but make 3-5 passes, you might cut through without having to "snap". This is the safest way.

 

I would suspect the driver, it seems they aren't getting full current. Any way you can test it?

Have you changed anything?