Algae Scrubber Basics

[Brummie]

If you go for Floyds tip about changing to a more roughed up clear screen, don't throw your old one in the bin. Pin the new screen to the old one for a few weeks. Growth seems to transfer easily between substrates as long as its growing well.

 

[thebanker]

Cool thanks for the suggestion. I'll try roughing up that screen with a hole saw on the next scrape. I'm kinda doing this ATS as a learning experience / experiment as I don't really need it on my tank.

Do black screens grow less than clear? I used the black because it was what I had on hand.

 

[Floyd R Turbo]

Well black just blocks the light, as does any colored screen material. With respect to algae scrubber screens, you generally want clear material because any miniscule amount of light getting to the base of growth helps the algae stay alive and thus anchored to the screen better. The "clear" material is not really clear, literally, but it transmits light.

After the screen is mature, the base of growth by which the algae re-grows comes from what remains in the holes after you scrape. If the material does not allow any light to get through to the algae in the holes, that algae will die off an your screen will be constantly re-growing this area and could technically never reach what we call "maturity". So I would make a new screen and do what BrummieGarf recommended - cut the old screen into strips and zip-tie it on for a week

 

[criticalencore]

Heres mine, 12"x16" lit on one side. It takes it about 2 weeks to fill up a cup

 

[GOSKN5]

Set up a simple waterfall scrubber using a spare HOB. Surface area is about 3.5 in X 6 in, single sided, lit for about 12 hours / day. Been going for about two weeks, starting to get some robust growth on the screen. Scraping the screen weekly. I've noticed less growth on the glass in the DT, so far.

How do you have the screen attached? Interesting concept with the HOB.. might have to try that

 

[SantaMonica]

Black also does not reflect. This plays a major part in floating surface designs where the whole inside is white texture. Even on glass-attached versions, it reflects so much light that I've purposely never harvested, and it got bright green all the way to the roots of 20mm (meaning, light was strong all the way through because of the reflection off the white.)

 

[jw85]

So I have a 125 gallon that I'm setting up as a freshwater tank. I had been planning on doing a sump/refugium as a place to house plants to help with nitrates, but I'm really worried about drilling my tank and flooding.

Would an algae scrubber work in a hang on back refugium? I'm trying to picture it my head, and I'm leaning towards no, but I thought I'd check. Surprisingly Google has very little on the topic.

 

[scolley]

An ATS will work in fresh water. Different algae, but with the same basic needs. However, it's been my experience that - generally speaking - if you are using plants as a key component in water quality management, you need a LOT of plants. I mean a whole lot. Ever seen a freshwater planted tank busting at the seams with fish? Likely not. Because you can't cram in enough plants to cope with a high fish load.

I've never used an ATS in freshwater, but I would assume the same thing would apply to an a freshwater ATS... A lot of green growth to soak up NPK (and urea) is a lot of green growth, whether it,s a tank chock full of aquatic plants, or an immense algae matt. As stated though, that's an assumption - no direct experience.

 

[Floyd R Turbo]

You could do the standard HOB refugium setup with an upflow scrubber in it, yes. You could also do a waterfall scrubber on top of the tank, a little trickier and would involve some DIY or an enclosed unit that could be set on top of the corner of the tank.

Drilling a tank is simple though. No need to worry about a flood unless you're drilling a full tank, which is just flat out stupid.

 

[Floyd R Turbo]

I used to run a 55 planted that was choc full of plants and about 100 livebearers and I still had to do 50% weekly PWCs, and I was running a Marineland C-360 with 2 huge bags of Purigen, bioballs, rings, filter pads, cleaning that weekly too and swapping the pads....]

Ha I found a pic

 

[lokii_37]

Where there is a will there is a way. I'm sure something could be rugged up to do a scrubber in your situation. A few posts back a guy made a scrubber in his bio cube over flow. It is only lit on one side. In his last update it seemed to be doing well?

Did I read correctly you are doing this for a fresh water tank?
You could get a HOB overflow if you really want to set up the scrubber in a sump like set up.

I have a100g freshwater also. Why not just put plants in the DT? A scrubber seems like a lot of work for a FW tank.

 

[jw85]

Thanks a lot for the quick responses all.

I have a 90 gallon set up currently with an all male African cichlid Hap tank. Unfortunately, they don't play nice with plants. Even though they are all open water predators, they dug them up / ripped them / ate them.

I currently do a 30 gallon water change every 3-4 days. I'm hoping in the 125 setup I can find a way to do like 50-60 gallon change once a week and not have to ever worry about nitrates. I keep going back and forth on whether or not it would be worth drilling the back of the tank (or buying a hang on overflow) and making a sump setup or not.

Thanks for the info Scolley - probably something I've overlooked is how many plants I would actually need to help me.

Don't worry Floyd - I'm not that stupid. The tank is sitting empty in my office right now as I'm still painting the stand and background. And that is a hell of a lot of plants, haha. I hadn't come across the up-flow scrubber. I'm going to look into that more.

Lokki - that is correct. I'll have to dig back through and find that post.

Edit: I will point out that I don't think the effort I'm going through is common with cichlids, as I was actually just referred to this site from a well known cichlid one.

 

[scolley]

Thanks for the info Scolley - probably something I've overlooked is how many plants I would actually need to help me.

This is an old picture of my 180g, the result of years of work trying to find the right balance between plants and fish. The pic shows the density of plants you need (vs. fish load) before you can stop worrying about algae growing on the glass and plants.

So if that is the density of plants required, how big an ATS do you need to accomplish the same thing?

PS - I've got better pics. But this one does a good job of showing all the plants, and all the fish.
PPS - That picture is actually a little deceiving. The tank is 24" front to back, but the fish are all up against the glass (just got fed), and the plants are pretty much in the back 12-18". So the fish look large, and the plants small - i.e. the fish to plant ratio appears higher on the fish side than it actually is.

 

[jw85]

That is a really good picture - thanks for sharing. Very cool setup. It helps reinforce that a 12x12 refugium in a sump probably wouldn't cut it.

I'm not sure if your question about the ATS was a pop quiz, but I thought I'd read on this site about 1 square inch per gallon assuming lit on both sides, so for my tank a 10 * 12.5 inch screen (though a longer one rather than a square one would probably work better if I was attempting it in a hang on back system)?

 

[scolley]

...It helps reinforce that a 12x12 refugium in a sump probably wouldn't cut it.

Yes. IMO a 12x12 refugium/sump with plants will be a drop in the bucket for the NPK absorption needs of a large tank. I get a real chuckle when I see reefers with a decent sized tank toss 3 or 4 mangroves into their sump, thinking it's going to make a meaningful difference.

 

[lokii_37]

Great looking tank scolley. One of these days I'll get some discus. Now that I'm into SW discus are not that badly priced compared to coral and SW fish.

 

[SantaMonica]

From direct experience and from others' reports, the main difference with FW is the long stringy growth. It does not curl and bunch up. So the growth will flow out of the same holes that the water does. This is fine as long as it allows enough growth before harvesting time.

But some installations will not allow long growth, and other installations allow the fish to get (or suck) the growth out of the scrubber. If you let the fish eat this, you probably won't need to feed them. But it will limit the filtering.

As far as sizing goes, it's not so much the standing crop of green that matters; it's the doubling time. Doubling in biomass requires 2X the nutrients as the previous biomass size. That's why algae absorbs so much: because it doubles so fast, as long as the requirements are met of light, flow, and attachment.

A standing crop of anything (plants, trees, algae) which is not growing does not absorb many nutrients because the nutrients are not needed for rapid growth. So the idea is to maximize photosynthesis ("filtering") which will maximize doubling in biomass, and will minimize the size needed for a give amount of nutrient uptake.

"Chlorophyll doubling time" is a whole area of study that is really fun to read

 

[scolley]

As far as sizing goes, it's not so much the standing crop of green that matters; it's the doubling time. Doubling in biomass requires 2X the nutrients as the previous biomass size.

Well that makes perfect sense. Thanks.

So to carry that forward... higher order plants (as in typical freshwater planted tank flora) do not double nearly as fast as freshwater algae? That would certainly be consistent with my less-than-successful freshwater planted tanks. I'm referring to the ones where I intended to grow freshwater plants, but principally grew algae instead. Anyway...

Since algae grows so much faster, the amount of green biomass - as seen in the pics Floyd and I provided - are not really representative of the mass of algae needed to do the same filtration. Correct? If so - and I have no trouble believing that - I'd be curious how much less algae will do the same job. Roughly speaking.

Granted, different plants (and different algaes) grow at different rates. And other factors will come into play that promote fast growth - or not. But it would be interesting to know just how little algae could accomplish the same filtration as higher order plants. One half? One quarter? Ten percent?

Anyone know?

 

[lokii_37]

i am getting a wierd "skin" on the surface of my algae. This skin spans the entire surface area of the screen. It cleans off pretty easily but I am worried it is preventing my algae from growing at its best. It is translucant green and breaks up easily. When the skimmer is running I cant even tell it is there but when I take the scrubber out to clean it, I can clearly see it.

any thoughts?

 

[Floyd R Turbo]

It might be a phase. How long has your scrubber been running? How long between cleaning?

When you say translucent, is that what you really mean? So it's pretty much clear, light shines through it vs blocking it?