Filtration Lighting L2 8 weeks growth, lighting adjustment?

The flow should even out after you start to get thicker growth, you can probably reduce flow a bit until that happens. The 35 GPH/in rule is a guideline, I've found that you can start much lower as long as you don't push the intensity too hard.

Have you harvested at all? If not, I would

Generally, you want to harvest/clean at maximum about 20 days from start-up, then about ever 14 days after that

You can pull out the screen as often as every 4-5 days and swipe & rinse to get rid of any diatom-type growth or slime. The yellow stuff is in this category, but that could be flow related.

When you harvest, don't scrub. First try, you should rub with fingertips & rinse. After that you can proceed to using the scraper, but just "drag" it rather than "chiseling" with it. A few months down the road, you might need to use the toothbrush, but use it very gently

 

7-14 days is ok

bump up to 5 or 4 o'clock, go to 18 hours/day

Don't angle the scraper into the direction of motion - that's the "chisel" method. You shoulnd't need this for a while. Just drag it with it either perpendicular to the screen or pointing away from the direction of motion

 

Hmmm...A few questions:

What is your flow?
If you haven't measured, what pump are you using and what vertical head?

What are your tank conditions:
Nitrates?
Phosphates?
Size?
Bioload?
Algae Issues?

Have you done this step above?

How many days growth is shown in the last pics you posted?

 

If I'm looking at that right, that's 6000 LPH => 1500 GPH max, the lowest setting I think is 48% (level 1) so that's over 700 GPH still. I'm thinking that even if the flow is 1/2 of that, it's way too much for an L2 actually. More on that later

You've got low nutrients, so this is good

Your feeding is good for the livestock you have. I'm not a fan of over-feeding just to get a scrubber growing. But when you average this out, you're probably at less than 1 cube/day, overall.

What I was asking about was this, specifically:

Versus a full cleaning, where you harvest the GHA. This above step is an interim step to keep the slimy stuff at bay. But this may not solve the issue

Your flow is too high (perhaps, way way too high) and this is what is causing the arcing. It may also be causing the yellow growth to some extent, and could be a factor in GHA not being able to anchor to the screen and start filling in. In my opinion, based on the nutrient levels and the tank water volume, this is the primary issue.

I mentioned earlier this:

To clarify, pushing the intensity too hard when the flow is lower than 35 gph/in would be something like cranking it to 2 o'clock when your flow was only 200 GPH. That might result in yellow growth, even with good nutrients.

None of these - actually, the opposite

What all this tells me is that you are trying to push the scrubber too hard, in an environment that can't support it at that level.

1) The feeding is OK for the tank, so like I said, I don't generally suggest increasing feeding to get your scrubber growing.

2) Reduce the flow to the scrubber. This will be a major reduction. If you have a spare pump that has comparable head/loss curve to the Rio 1100, I would use that, and dial it back to the point where you are just getting coverage on most of the screen, and no arcing at all. You would start out low, so that you weren't getting coverage on the far side of the screen from the inlet, and increase until you do cover that area, without arcing. You will leave it here for a while (possibly permanently)

3) Your lighting could probably use an adjustment but only after you fix the flow issue. You have a base of growth, so 5 o'clock or even 4 o'clock is probably OK. But back off the duration until the screen starts to fill in green more - go back to 12 hours/day. I didn't have the full picture on your tank before, so I apologize for telling you to extend it. It didn't hurt, but it didn't really help either...oh well.

I don't know if you can adjust #2 with a valve on the outflow of a DC pump, I'm not sure that's recommended. It might be OK. I know you can throttle back any AC pump this way, just not sure if that's the same rule with DC pumps.

 

That'll work too!

May not even have to do that much, just run under tap water and rub with your fingertips, or swipe your palm across it. Depending on the amount of slime left over, you may want to use the toothbrush and "drag" this across as well to get some of the yellow slime to detach from the screen and expose the mortar or plastic. Gently though, you can use a back & forth motion if that helps loosen the yellow stuff more, but you'll probably take some mortar with it (which is fine)

 

Looking better, I’d hold the course for now

About the false bottom - why would you need to take it out to check flow?

 

Flow shouldn’t change that much over the course of a growth cycle. You can try it after cleaning then put it back in. You don’t absolutely need it, but without it, you’ll probably get more bubbles into the drain and possibly some sucking sounds.

I wouldn’t overly worry about the flow. If you can see it covering most of the screen, you’re good

 

Seems to be getting better, but slowly. I would hold the course on the lighting intensity/photoperiod. Your nutrient readings combined with tank volume tell me that increasing anything might result in a growth reversal...it might not, but I would hope to see the growth fill in a little better before changing anything

You can "drag" the scraper across the green growth areas when you harvest, that should pull the growth off the screen pretty well, leaving a thin layer of GHA strands behind.

There rarely a reason to aggressively scrape, even the drag-method removes 90% or better of the growth typically. The exception is when you get a lump or ball of GHA growth that is strongly attached, that does happen, usually during the first few months, and you want to thin that out by scraping at it a bit more. Other times are when you have some other types of growth that are firmly attached in patches, something red or brown growth can get this way

Hope that makes sense!

 

Here's one of my Rev 4 L2 after it got to a full screen of growth for I think the first time

 

Here's a few more, just randomly picked a bunch. It's not a direct parallel to your because the growth on these is full coverage, but hopefully this helps give you an idea of how much I try to leave behind. Maybe 5% ish, but many times after the drag pass & rinse, it's less than that