Quantifying Biomass

[Garf]

Thought it was about time we did some comparisons of biomass per surface area of screen. Maybe some of the myths can be dispelled and get the most efficient usage data for scrubbers. I'll kick it off; (I know you need to do dry mass for it to be accurate, but wet mass will suffice for now)

Two sided waterfall, 200sq inch (100 each side), aerated, single side cleanings, 50watt LED growlight on one side, 40watts of 6 month old cfl's on the cleaned side, flow approx 2500lts hr over 13 inch width.

Harvest average 400grammes, 9 days

So 400g/200sq inch/9days = 0.2222 g per sq inch per day.

[Ace25]

You want just the screen or weekly harvest from the entire system? LOL. I just pulled out at least 2x as much out of my display compared to what I just cleaned off my screen. I don't have a scale to weigh it, but it was 2 'softball' size handfuls out of the display and 1 baseball size handful off the screen, all in a weeks time, and I have been slacking badly in the feeding department recently (pinch of pellets a day and a few cubes of frozen 2x a week).

[Garf]

You want just the screen or weekly harvest from the entire system? LOL. I just pulled out at least 2x as much out of my display compared to what I just cleaned off my screen. I don't have a scale to weigh it, but it was 2 'softball' size handfuls out of the display and 1 baseball size handful off the screen, all in a weeks time, and I have been slacking badly in the feeding department recently (pinch of pellets a day and a few cubes of frozen 2x a week).

Play fair Ace ;) just the scrubber. Not sure what a softball of algae weighs :)

[Floyd R Turbo]

Ace, what is going on in your tank that your scrubber can't beat that out?

Back to the topic, I do have a small digital scale I can try to remember to bring with me on cleanings. But how are you defining wet weight, dry weight, etc?

If I scrape and weigh without squeezing, that's wet. If I scrape then squeeze out the water with just my hands, that's not really dry, but not sopping wet. If I dry it out in an oven, that's really truly dry.

[Garf]

Your right Floyd, it needs to be standardised. I just wait and let it sit for a minute or so, on the cheeseboard i use for scraping it on (angled into the sink) until there's just a few spots of water a second dripping off it. Open to ideas though.

[Floyd R Turbo]

Squeezing, salad spinner, centrifuge, something like that...some way of purging the 'loose' water without the need to oven-dry the stuff.

[Garf]

How about a length of 4 inch drainpipe, with 7 count mesh glued on one end. Then a plunger (the full width of the drainpipe) of a certain mass, say 1kg. Leave it one minute, then weigh.

[Floyd R Turbo]

I think the mesh material should be much finer, so as to only let liquid through. Like micron rated stuff, filter paper (coffee filter), etc.

[Garf]

Ok. Pipe as described above for strength, place on a coffee filter that's put in the plug hole of the sink, pipe placed on top, retain coffee filter collection for inclusion in weigh up.

[Floyd R Turbo]

Something like that. Probably would still need a harder surface to press/squeeze through. I'm thinking of something. For drain tile in a window well, there is a cap that is made which has slots in it, like a strainer, so that rocks/etc don't go down the drain tile. You could lay a piece of #7 or #10 canvas over that, then the coffee filter, put algae on that, and something on top to squeeze the water out.

Something like this, I think this is not quite what I was thinking of, but you get the idea - more rigid...

http://www.farmandfleet.com/products/009271-advanced-drainage-systems-perforated-end-plug.html?utm_medium=shoppingengine&utm_source=googlebase&gclid=CIKRwoOL37YCFSNqMgodjQwABA#.UXWZwkqhxsI

or better yet, the metal or plastic from a drain strainer

http://kbrsinc.com/site/kbrs_products/drains_and_strainers.html

again, with canvas over it, then coffee filter. The coffee filter might break where the grating it.

Egg crate for that matter would probably work. Then just a flat weight, or a formica-covered board with weight placed on it.

[Floyd R Turbo]

I weighed my harvest from the doc's tank today, 14 days growth (all green, no dead roots!). Forgot to bring scale and squeezing equipment so I bagged it and took it home. Using my digital scale and subtracting the bag weight it was around 233g wet and 70g dry/squeezed.

I squeezed it first using an old hang-on QT tank / birthing trap thing, a piece of mesh, paper towel, and a water bottle with a squarish bottom to squeeze it out. After a few minutes I had an algae pancake. But I was able to squeeze a little more out with my hands, but not all might be able to do so, this algae is nice and all GHA no slime, at all.

Addition:

so that's 70g / 14 days = 5 grams/day over 24 sq in = 0.208 grams per day per square inch, but that's LxW so if you count surface area (LxW x2) it's half that, or 0.104 grams per day per square inch.

[Floyd R Turbo]

I just reviewed Garf's first post and I'm getting a little under 50% of his g/sqin/d harvest, but that's squeezed/dry weight. If I used the drip-dry weight of 233g, that's 233/14/48 = 0.346! Take that!

[Garf]

I just reviewed Garf's first post and I'm getting a little under 50% of his g/sqin/d harvest, but that's squeezed/dry weight. If I used the drip-dry weight of 233g, that's 233/14/48 (tel:233/14/48) = 0.346! Take that!

Yeah, I think my single sided cleaning may be skewing the comparisons a bit. I've included the area of both sides in the calculation but actual only harvesting half of the area every 9 days.

edit - but then again, the harvested side is 18 days, so probably evens itself out. I've gotta get my figure up. Ditching the worn out cfl's first. Also gonna harvest more regularly.

[Ace25]

Ace, what is going on in your tank that your scrubber can't beat that out?

Million dollar question, I wish I had the answer. I know the deep sand bed in that tank is one of the factors causing my issues. I have tried numerous things to resolve the issue (taking out sand/cleaning/baking it, and 'cooking' the rocks) but all my fixes seem to only last a month tops and then the algae grows back in force. I have major plans for redoing that tank, actually, had those plans for the last 2 years, just never seem to find the time to get er done. I know it is going to take 2 full days to redo the tank from scratch and my biggest fear is my delicate fish. They will have to be put in holding tanks during that time.

Right now I have a new ATS design in my head that I hope to build soon, one that I hope can solve most of the issues we talk about on here. It won't be a surge system due to the complexity of that, but it will have multiple screens and a new way to mount them and deliver water to the screen (not a pipe/slot method). It will be 4 small screens, 6"x6", and dual chambered (middle will have LEDs facing both directions), that way I can remove 1 or 2 screens at a time to clean and still have 2 screens in place in order to not shock the system at cleaning time, just to give you some idea of the direction I am going. ;)

I don't know how much the 'biomass' question plays into the health of a system because the system I have with all the algae problems in the display has grown at least 5x more algae per week on the screen for the past 4 years, while my other system I can go a month before cleaning and still can never come close to the amount I clean from the 75G system in a week, yet, that tank is doing 1000x better, no real display algae problem and corals are doing good. I think it just falls under the 'every tank is different' mentality (even though I used the same rocks/sand from my 75G when I setup the 60G).

[Garf]

Tried the squeezing technique and started at 295 grammes (this side is 100 sq inch, 9 days 2 x crap cfl's + 4 days LED growlight). After vigorous squeezing could only get it down to 155 grammes. So perhaps my dense carpet of algae holds a bit more comparative mass. Anyway, the calculations for this would be 155/13/100 (tel:155/13/100) so 0.119 compared to Floyds 0.104. However, that's trying to account for the fact I'm cleaning only one side at a time ie. the screen size figure of 100 is only half of the actual screen size. These figures may be more useful when tinkering with individual systems, rather than comparing different systems as we know, all systems tend to run slightly differently.

[Floyd R Turbo]

I weighed my harvest from the doc's tank today, 14 days growth (all green, no dead roots!). Forgot to bring scale and squeezing equipment so I bagged it and took it home. Using my digital scale and subtracting the bag weight it was around 233g wet and 70g dry/squeezed.

Addition:

so that's 70g / 14 days = 5 grams/day over 24 sq in = 0.208 grams per day per square inch, but that's LxW so if you count surface area (LxW x2) it's half that, or 0.104 grams per day per square inch.

Weighed the harvest again today: 16 days of growth, I removed one diffuser (Rev 1 L2) and about 1/2 way through the growth period, I had to remove the pump to move a Flame Hawk that likes to go to the sump, so I rinsed out the pump (wasn't really that dirty).

The result was a wet weight of 349 grams, dry/squeezed weight of 121 grams

Addition:

121g / 16 days = 7.5625 g/d over 24 sq in = 0.315 g/d/sqin, but converting to physical area (48 sqin) then it's 0.157 g/d/sqin

That's a 50% increase in harvest! Woo hoo!

[Garf]

I'm gonna keep the shorter cleaning period for a while and compare growth with new harvests, now my cfl's have been changed (about 7 months old). I like this method of quantifying mass. The algae on the last cleaning seemed to be more watery than I'm used to.

[Garf]

G.H.O.S.T. screen, second cleaning harvest of cfl powered side (probably 20% of guideline lighting);

10 grammes squeezed, 65 sq in, 7 days is 0.022g/I/day

[Floyd R Turbo]

Harvested the scrubber from the Doc's tank today - 17 days, 100g even

100g / 17d = 5.88 / 24 = 0.245g/d/sqin, /48 = 1.23g/d/sqin

[Garf]

Waterfall screen;

190g squeezed, 20 days, 100sq inch = 0.095g/day/sq inch. That's nearly three times the average growth that this screen produces when cleaned every 7 days.

Ive also saved the harvest to do a dry weight test at work (with high accuracy scales and a proper drying oven).

[Floyd R Turbo]

Garf, is that 100 sq in representative of one side of the screen, or did you harvest both sides?

For purposes of this thread/process, I think we need to standardize on one, I opt for surface area, because it allows for single side cleanings and horizontal, etc

[Garf]

Yes Floyd, gonna keep to one sided cleanings. It seems to give stronger attachment than when I was letting both sides get thick.

[Floyd R Turbo]

Harvested the scrubber from the Doc's tank today - 17 days, 100g even

100g / 17d = 5.88 / 24 = 0.245g/d/sqin, /48 = 1.23g/d/sqin

This should have read 0.123 g/d/sqin...just caught that

[Garf]

Dry weight test completed;

Container weight;
http://i1269.photobucket.com/albums/jj597/Garf1971/432a29a7181f9ad4b7cb0bf00a968e89_zpsca60638f.jpg

Squeezed mass and container weight;
http://i1269.photobucket.com/albums/jj597/Garf1971/e870433df501cf4f0fbcce709146d075_zpsef171f42.jpg

Dried algae and container weight (3 hours @ 110C);
http://i1269.photobucket.com/albums/jj597/Garf1971/70969357ae9df8e78ba286c89b37208b_zps18c6b51b.jpg

calculation resulting in a dry weight ratio of 5.25% of squeezed weight
http://i1269.photobucket.com/albums/jj597/Garf1971/0627e48938ff9be2168aad499cc51c82_zpseb6f6d69.jpg

[Garf]

To add a bit of relevance to the dry weight status, Randy F wrote this a while ago;
http://reefkeeping.com/issues/2006-09/rhf/index.php#21


For example, Caulerpa racemosa collected off Hawaii contains about 0.08 % phosphorus by dry weight and 5.6% nitrogen. Harvesting 10 grams (dry weight) of this macroalgae from an aquarium would be the equivalent of removing 24 mg of phosphate from the water column. That amount is the equivalent of reducing the phosphate concentration from 0.2 ppm to 0.1 ppm in a 67-gallon aquarium. All of the other species tested gave similar results (plus or minus a factor of two). Interestingly, using the same paper's nitrogen data, this would also be equivalent to reducing the nitrate content by 2.5 grams, or 10 ppm in that same 67-gallon aquarium.

Obviously these studies were on macros, sorry for that, there's not a lot of info on filamentous stuff that I could find. Perhaps SM has got some research hidden away somewhere.

Note the plus or minus a factor of two reference. This is quite a large range depending upon species.

[Floyd R Turbo]

Harvested the scrubber from the Doc's tank yesterday (6/11/13) - 15 days growth, 101g (311g wet)

101g / 15d = 6.73 / 48 = 0.140g/d/sqin

N=0, maybe 0.1 or 0.05

P=0.01

Both tested I think Sunday-ish.

[getmealemon]

Garf, thanks for this article http://reefkeeping.com/issues/2006-09/rhf/index.php#21

Not seen it put into numbers like that before.

[Floyd R Turbo]

Garf got banned. You can find him on my site if you wish to contact him. Not even sure he'll see this post.

[getmealemon]

Really?! What for? What's your site? Can PM me if either can't be mentioned in thread. Cheers

[Floyd R Turbo]

Click my sig links to go to my site