Growth Help

I asked a few questions which were answered over e-mail, here they are:

Your growth seems to be a mixture of some rather dark algae, which is usually indicative of high nutrients, as well as some areas that look like they are getting too much light. That's kind of an odd combination, so here's a few questions for you:

What you are seeing might just be the normal phase while the screen matures. The growth around the outer edges suggests that there is enough nutrients for algae to grow well, but maybe not enough under the intensity that is right at the center of the screen (where the blues are). It should continue to fill in over the next few weeks or so. There might be a little bit of lower flow right under the ring, where it "parts" the water (into an inverted "V"). This also will fill in as growth in the higher flow areas diverts flow toward the center.

While I haven't generally considered this an issue or an item to "fix", you might take some sandpaper or a file and round off the rotatable ring such that it has a more elliptical or circular cross-section, so that it wouldn't cause the water to divert around it, rather it would "wrap" around it. Eventually I want to have the rings manufactured, I've looked at a few options but cutting them out of couplers is really simple and easy, so it hasn't been high on the priority list.

You might try letting it grow for a little longer - try waiting 10 days. It does look like you have holes that are starting to fill in, and you can probably give the screen a good scrape at the next cleaning, then a light rinse and rub.

That is correct. You don't want to change these until you get really solid and consistent growth, then change them one set per fixture at a time, such that you haven't jumped up intensity on two opposing sets (directly across from each other)

That's a good start, I usually recommend starting with 9 hours/day, that might explain the lower growth spot in the middle. But the bottom line is that it is growing algae, and you don't have a tank algae or nutrient problem, so you're on the right track. You can try 10 hours/day but I don't think that will make a huge difference at this point, so I would recommend leaving it as it and letting it cure

The "guideline" flow rate is 35 GPH/in of width. For the L2, this is 6" wide or 210 GPH or 800 LPH (after head loss). I usually recommend a Rio 1100 for regular flow (that is 290 GPH, after head loss it's usually 240) or the Rio 1400 for "high flow". So you're about double that, which may be a factor. This also may be causing more flow diversion around the ring as the higher pressure water will shoot past it more instead of wrapping around it.

Now, my theory on this is that a very high flow rate while starting a screen can tend to prevent growth from attaching because, well, there is a high flow rate. So initially, I recommend going with the standard 35 GPH/in rate until you get a base of growth. But, each case is different. In your case, it appears that you have good conditions for growing alage. The algae you appear to be growing is brown, which would initially lead me to conclude that you have high nutrients, but you really don't. What you do have is high nutrient delivery, meaning you are pushing a lot of volume across it, so it may be that under those conditions, the brown algae is the preferential type of growth.

So the answer could be to decrease flow to allow the GHA to kick in.

Another answer would be to increase the duration and/or intensity of the lighting. This is usually what I recommend to do when you have cured your screen, have good consistent growth of GHA, but you still have nutrients or tank algae. Increasing the duration of the photoperiod can be used by itself to filter longer, usually without "burning" the screen. If you increase the intensity (via jumpers) I have been recommending that you also increase the flow, so that more nutrients are delivered (which would prevent the screen from turning yellow due to lack of nutrients).

But in your case, your screen is not mature yet, so it's kind of a mixed situation. If you don't have algae or nutrient problems, I would decrease the flow a bit and see if the screen fills in. And rond off that ring (but don't decrease the inner diameter of it, you want it to still hold tight to the pipe)

Hope that helps, and I'll get your upgraded slot pipe and the light/spray blockers off to you ASAP with the rest of the UK bunch!

 

I've seen that "big clump" type of growth before but I don't have any way to explain it. Algae just seems to get a foothold in one particular spot very well. Eventually you will not see this effect but if anyone has any other idea why this happens I'm game.

I would just clean off the thick growth areas, i.e. the clump, and give the rest of the screen a light swipe with the small toothbrush to loosen any weaky attached algae, rinse, and let it grow for 10-14 days. I clean most of my screens every 14 days, but that's more of a convenience for 2 of them (customer tanks, I make my rounds every other Monday) but it seems to work OK, so I started keeping my personal tanks on the same 2 week cleaning rotation. As long as you don't have so much growth that light gets blocked and you get detachment, you're fine. When you clean the screen, if you see an area at the screen underneath green growth that is brown and kind of slimy, then that is a sign that you waited too long. So it's hard to tell just by looking at a screen that you waited too long, you have to clean and examine it.

 

That makes sense @Garf, if that holds true, it would support a rationale for not cleaning a screen initially for a good length of time. No vigorous cleaning for sure, that has been a recommendation of mine for a while. But are you recommending no cleaning at all until filamentous growth starts?

 

That looks pretty decent for 7-10 days. The growth is dependent on a few factors, mainly light, available nutrients, and flow

Your screen is very mature, so if you still have measurable nutrients in the water column (mainly N and P) then you can increase the flow and photoperiod a bit to take those down.

Start by testing your N and P levels and post the results here.

Do you have any nuisance algae in the display tank? If so, where is it? Rocks, glass, overflows, etc

 

Up the flow a bit, and extend the photoperiod to 10 hours. Let it grow for at least 10 days, 14 if you can. I let most of my scrubbers go 14 days. The growth will "pile up", if you take off the light fixture to check it, the growth will be high in the center (up against the window) and drop off on the sides. When the water/growth line on the sides is about 1" off the false bottom (and probably 1" or so from the bottom edge of the light blockers), it's nearing time to clean.

If you continue to get good growth, after the next cycle you can add a bit more flow and increase the hours to 12

 

No problem jumping in, but it's fine to start your own thread too with pics and description. Here to help all, DIY scrubber or bought from someone else even! I can even move a few posts over to a new thread if you want

It would help to have a description of the scrubber: size, flow, lighting type (LED, CFL, etc)

16 hours/day might be fine depending on the lighting, could be too much, but if you are getting growth and the screen is filling in, then you're probably past the stage where that matters. When you are running low bioload, i.e. not much for N and P, then you run the risk of cooking the screen -> photosaturation. If you're running LEDs and you don't see bare spots in front of them, then this is not an issue. However I've seen screen mature nicely and then take a dive, not really a rhyme or reason to it, much of the time it depends on the specific circumstances of the system, and even then, it's just a best guess as to what is going on.

@ainsy while this thread is getting bumped, do you have an update?