Help needed

Based on the videos, I don't see anything glaringly wrong.

Generally, I prefer to use lights that are growth-spectrum oriented (red/blue or red/violet) but this is not an absolute rule - algae will grow under most any light with the right conditions, whether it's the optimal spectrum or not. Your algae seems to be growing well.

The intensity of the light might not be quite enough, if this is the issue then as the growth gets thicker, it will tend to detach as the underlying layers don't get enough light and become weak. But I did not see widespread detachment (like, large sections sluffing off). You might get a chunk here or there, depending on how mature the screen is.

So, a few questions:

What are the dimensions (length and height) of the screen?

What is the total water flow you are providing the screen? Estimate if you have to, or post the pump info and your vertical rise (from the water level in the sump to the slot pipe)

How many hours/day are you running the lights?

Can you provide a link to the light fixtures you are using?

How often do you harvest the growth?

When you harvest, how aggressively do you scrape off the growth? (i.e. how much do you leave behind, do you scrub the screen with a brush, etc)

That's a start - I might have more questions

 

Ok, so about 8-1/4" x 11-1/2" or about 90 sq in. If you go by the cube/day sizing guideline, that's big enough for about 8 cubes/day of feeding (if properly lit and provided enough flow).

at 10 LPM, that's 150 GPH. For an 8" wide screen, that's about 18 GPH/in. So if you're half that, that's less than 10 GPH/in. I would say that your flow (for that size screen) could be a bit too low. But again, you've got good growth so that's not a hard & fast rule being broken necessarily

That's OK

Based on my lighting guide, Lighting: LED and specifically this part:

If you have 90 sq in and 16 W per side, that's 0.17 W/sq in on each side. So that is pretty low, which might explain detachment

This link didn't really work, I think you might have pasted the wrong one?

Good

If that removes enough, that's fine. You'll want to leave at least 25% behind, maybe more depending on how long you've been running the scrubber (the newer the screen, the less aggressive the harvest)

That's OK, but IMO the better way is to partially clean both sides with a pattern that intersects. Like making a "#" type of pattern on one side and an "X" pattern on the other - so that you expose the base/screen on alternating sides. Also, if your light is too low intensity, clearing off more of the screen is a little more important IMO

Link? 5 minutes is pretty horrible performance...may not have been sealed

Overall:

I think you could have better performance by making your screen narrower. Leave it the same length, just so that you have good drainage to the sump (meaning, it doesn't have to drop several inches and then splash everywhere). But essentially, you would have an "active" growth area that is concentrated in the center portion of the screen.

Making it narrower and not changing the total flow will increase the GPH/in of flow, meaning, you will have a higher rate of flow over the narrower screen, if that makes sense. Higher flow means more turbulence, more nutrient exchange, and better utilization of the lights that you have (smaller area + same light = higher W/sq in ratio)

I think your lights are positioned well, but if you can lower the right one slightly so that it's shining on the same area as the left light, that might work better (we're talking a very slight increase in efficiency though...)

Run the lights 24/7. Your screen is mature enough and your nutrients are high enough to handle it. Algae is not the same as plants - the rules do not apply equally. If you've read elsewhere that "algae needs a dark period" that is dead wrong. The truth is 24/7 will work fine, but that doesn't mean everyone should run lights 24/7 - it's very dependent on the individual system (tank) and scrubber design (especially the lights).

Your system has high nutrients, you have decent growth, and your screen looks mature - so it's not likely that running your lights 24/7 will cause a problem (rather, it will help). Make the screen narrower to concentrate the flow to a smaller area and that will concentrate the growth so that the algae that does grow is stronger. Right now, you're over 2x the size screen according to what you are feeding, and that's my "rule of thumb" (don't exceed 2x the size you need) so that is a factor in my suggestion to make your screen narrower

Sorry if this got repetitive but I'm typing quickly - busy week

Let me know if this all raises more questions, here to help!

- Bud

 

Not really, I haven't kept up on what fixtures are available - they change so frequently

 

I don't see coraline on the screen, I see what looks like detritus or dead algae. Do you rinse the screen off well under running water after you harvest?

That greyish-brown buildup on the screen (under the algae) needs to be rinsed off. I'm thinking I would actually scrape the screen fully and rinse well and let it grow back. I would also recommend that if you take out the screen at least every 7 days and perform a "rub & rinse" where you (quite simply) gently rub the screen with your fingertips while rinsing under room temperature tap water. This will loosen and remove any detritus and/or slimy algae, and will also cause detachment of any weakly attached growth.

 

Yes, generally the brighter green is what you want. Did you change anything?

 

I would rub & rinse, try to leave any GHA behind

IMO it's more about GHA getting a foothold than organics. I think the brown slime is more "primitive" for lack of a better term - it grows quickly and easily.

GHA grows faster in freshwater because SW GHA has to use a protective osmotic layer to keep the salt out. So in FW scrubbers, you get fast growing super-fine GHA that detaches easily, but less of this slime type growth (if any at all). The SW GHA has to be more robust and that means it takes time to get a strong foothold on the screen. So you have to "clear the path" more frequently so that the brown slime doesn't prevent this.

 

room temp tap water

 

Definitely improving!