Backyard Aquaponics
A place to discuss aquaponics

Still having problem with this,

using:
bedless system , so need tank for bio-culture exclusively

all i see are ppl using are "hot wheels rims" and such -- is this the best there is??

I have seen ads for wire brushes, and filter sponges, but cannot confirm if they are food grade for my veggies and fish, --- do these work??

also cannot get surface area to volume index for any of these , so i cannot calculate how much i need either.


please help on this!!!

ps-- I really hope i do not need to use the hotwheels...


THANKS!!

Have you checked Kaldness K1 media? It is a fairly commonly used media in aquaculture and has a total surface area of 800 m2/m3 and a protected surface area of 500 m2/m3.

Do a search for MBBR, Moving Bed BioFilter, MBBF, and Moving Bed BioFilter. They are the same thing but those terms should catch it. It's basically an aerated tank with K1 or similar biomedia. The bacteria aerobically break down and process the waste. You'll also need something to remove the solids prior to the MBBR. Radial Flow Filters or Static Upflow Filters will do this for you. Plastic Bottle caps can be used in a Static Upflow Filter (or you can use K1 if you have extra). A pic of the bottle cap filters is here http://backyardaquaponics.com/forum/viewtopic.php?f=18&t=16235&p=528174#p528174

interesting, yes it is the K1 that looks like hot wheels rims, so is this the most common method used?
is there anything with more surface area?


Again this:
I have seen ads for wire brushes, and filter sponges, but cannot confirm if they are food grade for my veggies and fish OR does food grade matter?, --- do these work?? I just wonder cause they seem like they would have a higher BSA

I would asume that a pump filter sponge would need to be food grade for the fish, even if they are not being eaten by people. ??

I like the bottle cap idea!
also how would i calculate surface area for those?


...will definitely have swirl filter and the like

It is pretty common. I don't know of anything with more surface area. But remember not everything with a high surface area is good. You want the usable surface area i.e. some media is marketed as 10,000 m2/m3 but actual usable area is less. I don't know about wire brushes. No experience with filter sponges. If you get anything that is for aquaculture or aquaponic, I would consider it food safe.

The bottle caps aren't really for biological filtration, they are for mechanical solids filtration prior to the biofilter. You probably could use them for biofiltration but part of the reason the K1 is nice is that it self cleans by being good at tumbling and the spokes give it a high usable surface area in relation to it's size. I'm not sure how good the bottle caps would be at the self cleaning or usable surface area - it might be worth a try . I'm sure they'd work but I'm not sure how well. Seems like the surface area of a bottle cap would be the surface of the circle on top and the cylinder that forms the sides but you'd have to multiply each result times 2 for the front and back. I'd probably ignore any serrations in getting the estimate.

I thought about using the brushes at one point and they look pretty good but it's easy to clean the K1 by aeration and that's pretty hard to beat. Sponges might have there place but probably not for the main system (maybe for rearing young fish ).

As far as safety and being food grade, it's whatever you're comfortable with. Many plastics that aren't specifically labeled food grade are probably safe but the manufacturer didn't care if it was tested. I've mostly used HDPE (High density Polyethylene). There's also structural PE foam which is what Rubbermaid stock tanks are made of and I have some of those also (cattle drink from it but it's not labeled as food safe). I think I may have used LDPE and Polypropylene at some point as well. You also should consider if it's recycled plastic or virgin plastic resin.

Well... you wild guess-timate it.

It is unlikely that you'll fill up a barrel will identical bottle caps, but if you can make some assumptions and toss out the hard stuff that you won't be able to easily account for... like grooves in the bottle cap sides, threads, and differences between the outside of the bottle cap and the inside of the bottle cap....

The (B) surface area of a bottle cap would be 2 times the area of the circle top (A), plus 2 times the surface area of the vertical open cylinder (C) created by the sides of the cap. In a formula that would be:

A = πr²
C = 2πrh



So the variables are 'r' - radius of bottle cap circle top, and 'h' - height of vertical sides of bottle cap

Therefore the surface area of bottle cap inside, outside and top is:

B = 2 x πr² + 2 x 2πrh

The 1st bottle cap I measured was 30mm diameter (r = 15) with 10mm height (h = 10):

B =2 x π x 15² + 2 x 2 x π x 15 x 10
B = 3298.7 mm² = 5.1 in²

Google Calculator for: 2 x π x 15² + 2 x 2 x π x 15 x 10

That is 3298.7 mm² (5.1 in²) of surface area for a 30mm diameter, 10mm height bottle cap.

To calculate surface area for a bottle cap with 30mm diameter, 15mm height, change 10 in the formula above to 15 and recalculate to get 4241.2 mm² (6.6 in²).

But do you really care? Of course you do or you wouldn't have asked!

So how many fit into a given area? This research paper shows how they calculated the use of half caps as submerged aerated filter medium. They used bottle caps with a surface area of 2900 mm² (slightly smaller than my 30mm diameter, 10mm height caps above) and found that 2617 caps cut in half fit in 30 liters. I think for K1 media it is recommended to fill a tank about 40% with the K1 media for a proper boil. Running with those numbers, a 200L barrel should hold 80L of media, or about 7000 bottle caps cut in half. As far as how much one needs, I think it should be calculated based upon how much fish food will be processed. Figure out how much you will be feeding however many fish you plan for and the size of the perfectly sized biofilter can be determined. The K1 folks claim 1 gallon of K1 media in a moving bed filter should process 2 ounces of 40% protein food, per day. Filter manufacturers rate it less than half of that (0.6 - 0.8 oz food / day.)

K1 media folks say 800m² / m³ of K1 media. There are 264 gallons in a m³, so 800m² / 264g = 3m² of surface area per gallon of K1 media to process 2oz of 40% protein food, per day. 3m² is 3,000,000 mm² or a little more than 1034 of the bottle caps used in that study cut in half. So 2617 caps in 30L means, 87 caps per liter or 329 caps per gallon. 329 caps cut in half per gallon with a total surface area of 954,100 mm² per gallon. That tells me that bottle caps have about 1/3 the surface area of K1 media. So you'll need about 3 gallons of bottle caps (cut in half) to process about 2oz of 40% protein food, per day. Factor that downward by how much you trust the K1 media folks numbers vs the filter manufacturers' numbers.

So, the 7000 caps cut in half to fill a 200L barrel 40% provide 20.3 m² surface area which should process 13.5oz of 40% protein food, per day, going by K1 media folks' numbers or 4-5oz of 40% protein food, per day, going by filter manufacturers' numbers.

How many of your fish would you feed with 110g - 140g of 40% protein food?

Does that help?

I think the wise aquaponist would ask, WWAD? (What Would Andy Do?) And then go study that Crappy Basil Grower's bottle cap up flow biofilter.

Uh, someone please double-check those numbers. Yeah, right!

--
Sam

omg! maths! stu will cream his pants when he sees this!

Sounds like it would work. I'm not sure how they cut the half caps but having half caps should help the media tumble. However you cut them try to avoid tiny bits of plastic getting into the system.

I checked the math up through the area of the bottle cap and it's right so far - that's about where I decided to pass out from exhaustion

If you aerate these they'll work as a biofilter but not as a solids filter. For a solids filter you don't want to aerate them - like Andreas setup. His does some biofiltration but the majority of that is done in his Deep Water Culture beds.

Edit: One last thing - when figuring how much media you need it's probably a good idea to at least double the amount. The amount K1 can process is likely based on optimum conditions and most of the time you probably won't be operating at these.

Hahahahahaaaaaaa

I've always said, "Math is Fun!" But this takes it to a whole new level.

Seriously, of course that is just an example of how to get a general idea of the numbers you seek. If doing a real experiment to figure it out, at least you have a reasonable starting point. It was interesting to find that the researchers cut their caps in half. I hadn't read of anyone doing that before. An aquaponist has a great advantage of bringing together research of various sciences (waste management, fish care, horticulture, fluid dynamics, zen, etc. etc.) and while we might be able to spin them better than anyone else, we don't have to reinvent all of the wheels. Wastewater management is all about filtering and cleansing the water -- an important skill in Aquaponics. We benefit from well trodden paths and yet still have opportunities to blaze our own. And... one is not required to cut their own way through the jungle with machete to enjoy aquaponics. If someone would rather stay on the pavers and reap the rewards they can do that too.

--
Sam

ya, maybe not bottle caps then, for this I think i would rather spend more to have smaller volumes, I will stick with the k1 if that is the recommended.

is there a k1 that has more surface/vol or recommendation of where to buy it?
http://www.alibaba.com/product-detail/M ... 30299.html
according to that image I would want the PE03 correct, with more sa?

also on the side I am thinking of what other shapes would produce better, if any ideas about this let me kno!


I am looking at about 200 plants to start(and will double plant count in mid summer, and double again for next year to 600-800), doing lettuce, spinach and cilantro btw..
so for 840 plants:
1 plant = 1/9 m2 or 1 sq ft
11lbs of fish per 1m^2 of plant
so thats 1023lbs of fish required...
and i need 3 gal of water per pound of fish
so thats 3070 gallons of water ....

FOR BSA:
25sqft bsa per pound of fish
so i would need 25575 ft2 of BSA
OR 2841m2 of BSA
so if the k3 is 1000m2/m3
then i would need 2.8m3 of K3
which is 740 gallon pail of k3???

hmmm.... that doesnt sound rite? maybe i size my plants too big?

EDIT: that was 3070 gallons of water for fish tank only....

As mentioned earlier, the standard K1 media is 800m² surface area per m³. The new K1 micro media is in a smaller form factor which results in 950m² surface area per m³. There are plenty of other similar things besides the official "K1 media". Has anyone here tried using cut up drinking straws?

K1 Micro



Columbia Water Gardens ships K1 media to Canada at a supposedly pretty competitive rate.

--
Sam

I can't recall anyone using the straws but I think it has been mentioned in the past.

Not a big deal but the four spoked K1 media is a bit more prone to being crushed than the 5 spoke types. I haven't been looking lately but the micro version was super expensive about a year ago.