Algae scrubber not getting the growth I expected

Can you post a pic and some more information about your tank and scrubber?

Things like:

Tank size & livestock
Feeding amount/day
Screen size
Flow
Lighting (photoperiod, intensity, light type/brand/etc)
How often you harvest, and how aggressive you clean the screen
plus pics, lots of pics, from different angles, before/after if you have them

Here to help! I'm in/out today so it might be a day until I get back to you

 

I think this got auto-corrected? For the feeding, can you break it down by how much you feed per day or each type?

See this for an idea of what I'm asking for:

Algae Scrubber Basics - Planning Your Algae Scrubber

Specifically:

The new rule is based on cube-equivalent amount of food fed daily, regardless of how many gallons you have in the system. You need 12 square inches of screen illuminated on BOTH SIDES with a total of 12 watts of fluorescent light for 18 hours/day for each cube-equivalent fed into the system per day. That means 6 watts per side of real wattage, not equivalent wattage. LED wattage is addressed separately as it has a different set of rules.

The cube-equivalent is defined as any ONE of the following:

1 frozen cube
10 pinches of flake food
10 square inches (60 sq cm) of nori
0.1 dry ounce (2.8 grams) of pellet food
3.25 mL of liquid coral food

If you feed something else and are having a hard time determining the cube-equivalent, then take the daily amount of food, put it in a blender with some water and puree it well, then strain it using a coffee filter (or a rotifer sieve if you happen to have a spare one laying around) and pour the food into an empty Ocean Nutrition or other cube-type food tray, and you will have the cube-equivalent for that amount of food.

 

Maybe 1-2 cubes, depending on the weight

2.5 cubes

How much per week? Probably not a huge factor

Overall I'd say you're at 4-5 cubes/day on average

That's a large screen, 14 cubes/day, but

Algae Scrubber Basics - Lighting: LED

So 120W of off-the-shelf lighting at 0.25W/SI, that's for 30 sq in of screen, but that type of fixture might be on the higher end

which would make it 2x that or for 60 sq in of screen, that's probably more accurate here. But the screen is 168 sq in so no matter how you look at it, the screen is probably under-lit, which is fine, you just would de-rate it down to the lighting, or about 5 cubes/day

That's not written in stone, every scrubber is different. What would be helpful is pics of a full screen of algae before/after you harvest.

 

OMG I'm a total moron today.

0.25W/sq in x 168 sq in = 42W for low, 84 for good level, I had that totally backwards. Ugh

The only addendum to that is that you need to use the actual wattage drawn by the fixture, not the "rating" - because of this:

I'm not sure if you have a link to that fixture where it lists the actual watt usage, but that's the number you would have to go by

More in a minute, I have to take care of something

 

Ok, sorry...had to attend to a sick dog (back injury)

So with the lighting being more likely to match the screen, that's a slightly different situation.

the other piece of info I don't have is the photoperiod - how many hours/day do you run the lights?

Regarding the flow:

You're good there with 12 x 35 = 420 GPH, this is just a general target, you can operate over a rather wide range. Generally you are wanting to match intensity and flow as those are "instantaneous" factors (with respect to photosynthesis) and this is tricky to do without dimming. So that could be part of this.

Now, going back to the original question...let's take a step back and I'll ask this:

How's your tank?

That's what matters. If the scrubber is doing the job, then you really don't have to worry much about the exact type of growth you are getting. "Chasing Algae" is a term that I just coined right now with this post. World's First use of that term lol (inside joke). It's similar to "Chasing pH" - if you know what that means, then "Chasing Algae" will make sense...trying to get the "right" growth just for the sake of growing it isn't necessarily...um...necessary.

The "fluffy" growth, or thick mat growth, might be a result of a particular tank/scrubber combination, or a particular design. So you might have room to optimize, if nothing else.

But if your tank is free of nuisance algae and nutrients are under control, fish and corals are happy - you might just stay the course.

However if you still have issues, then it's worth digging a bit deeper

You're welcome!

 

What about this?

 

No "burnt" spots or "bare" patches in front of the center of the LED chips?

Growth overall has been pretty consistent from one harvest cycle to the next?

 

How large of a piece? Was that happening initially, is that why you put it there?