Backyard Aquaponics

BioFilter designs?
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Author:  Sleepe [ Jul 29th, '15, 13:40 ]
Post subject:  Re: BioFilter designs?

"One of the few internet posters not answering with guesses for everything"

Remind me of this when I disagree with you scotty. :bootyshake:

Author:  scotty435 [ Jul 29th, '15, 14:58 ]
Post subject:  Re: BioFilter designs?

:lol: I just try to give the best answers I can, lots of room for improvement I'm sure.


Author:  boss [ Jul 29th, '15, 18:26 ]
Post subject:  Re: BioFilter designs?

Will do, Ryan. Thank you and Scotty

Author:  boss [ Jul 29th, '15, 18:38 ]
Post subject:  Re: BioFilter designs?

Looking at the writeup on KI media you posted a link to Scotty435: Details:

K1 - 10mm X 7mm or .39in X .28in - support about 35 pounds of fish per 2 cubic feet

K2 - 11mm X 7mm or .43in X .28in - Support about 42 pounds of fish per 2 cubic feet
K3 - 25mm X 12mm or .98in X .47in - Support about 33 pounds of fish per 2 cubic feet

Kaldnes Bio Filter Media suited to fluidized or moving bed tank systems. Kaldnes can support about 35 lbs of fish per 2 cubic feet of media, where fishes are fed 1.5% of their body weight per day. A safer measure is a maximum of 0.55 lb of food per 2 cubic feet used, in order to ensure the best possible water parameters are achieved.

How It Works

Kaldnes bio media provides the maximum active surface area for the bacteria to colonize, more than other types of static media. It is this process which removes harmful ammonia and nitrite from the water.

As the Kaldnes media moves within the filter, it causes the old dead bacteria on the outside to be displaced. This makes space for younger, heavier feeding bacteria to rapidly colonize. Within the wheel is a protected surface, which enables colonies of bacteria to naturally follow their life-cycle of maturing, dying and then fueling the latter stages of the nitrification cycle.

Unlike foam, matting, or other forms of static filtration media, the Kaldnes media is designed to move freely within your filter. The constant chaotic movement of the air causes the media to self-clean and thus requires no maintenance. This allows the filter to reach optimum effectiveness without the disturbance of periodic cleaning, avoiding unnecessary loss of bacteria within the filter.

This is an outstanding description. Sorry it's a little early in the morning for adjectives. One thing is for certain, I am going to build an MBBR. I love this. Now all I need to do is start learning about the feed load Ryan and others are asking me about.

Author:  boss [ Jul 29th, '15, 19:58 ]
Post subject:  Re: BioFilter designs?

If you end up building a k1 mbbr ( or other media), post your maximum feed input into the system (daily) and I'll run some numbers for you :)
Okay, I guess I know more than I did a half hour ago :thumbright:

One of the many things I am naive about is the species I want to grow. Trout was my choice. I hope my inexperience growing fish doesn't make this a poor first attempt. Without any media beds in the system yet, something that I hope to rectify today, the water temperature in the 10k lt FT has always measured 68F whatever time of day I read it with an infrared thermometer.

One more note of importance, this isn't a RAS, however I do wish to increase my fish stocking density beyond what the initial four 1'X2'X6.5' media GBs can support. My goal for this system is fifty to 100 trout year round. Now of course I don't know my rear from a hole in the wall, but I was thinking of not harvesting all the fish at the same time or all of the fish all the time.
Wait, that isn't clear.
Here, how about I tell you what my goal with this system is.
I will be 62 in January. I have a strenuous job at which I work four days per week installing wireless Internet in rural and mountain locations. I don't know how long I can keep this up even though I love it and want to keep going , I have to look to the future and retirement. Like many Americans I never planned for retirement, heck I didn't think I'd live this long. Anyway, my retirement depends a lot on subsidizing social security income with food production for myself and my wife.

The feed rate therefor will be for an initial stocking of trout fry which I still have not figured out how to get from neighboring Colorado. I'll call the hatchery soon and see when they come this way next, and plan that to coincide with our system finally cycling. I'll wait until I learn a lot more about the chemistry of aquaponics to decide about the 50 or 100 fish. The bottom line is this system will feed one household with the possibility of a few fish and veggies to give away to family friends and visitors.
It sounds like my intention to keep many variations of age fish, makes figuring the feed rate much more difficult doesn't it? Well at least I decided to drop the idea of catching fry and small trout locally. Can I make a more informed decision by looking at the feed rates of 50 trout, then 75, then 100?

Thanks for all your input and advice.
Brian Rodgers

Author:  boss [ Jul 29th, '15, 20:07 ]
Post subject:  Re: BioFilter designs?

On the Kaldness media, I think I heard the K2 is the better style "K2 - 11mm X 7mm or .43in X .28in - Support about 42 pounds of fish per 2 cubic feet"
Okay, two cu ft of K2 equals about 14 US gals. How much K2 is optimal for my 53 gal - 200Lt barrel?

Author:  scotty435 [ Jul 29th, '15, 23:53 ]
Post subject:  Re: BioFilter designs?

The 5 spoke version listed as K2 is the one I used. The original K1 is more prone to collapsing and has less surface area. K3 also has less surface area.

I'm not sure about how I'd figure the feeding. I found these tables, FAO is usually pretty good and they might give you a start -

boss wrote:
How much K2 is optimal for my 53 gal - 200Lt barrel?

That kind of comes back to how many trout you want to stock, what size they are, how big you want to grow them and how much aeration you can provide. If I understand right it's recommended that the MBBR be 50% up to a maximum of about 65% of the reactor volume that can be filled with media. There is a recommended amount of aeration based on the surface area of that media. Here's a link with some good rules of thumb - FYI - I'm running at about 30% filled with K2, I don't think it's critical to hit the 50% (might affect the self cleaning but I can't tell that it does) - as long as you're aerating enough and have enough media, the bacteria will get the job done.

FYI - My experience is that it gets more difficult to keep the media moving as you add more, especially when it's new so you may want to start with a couple of cubic feet and add more later if you want it. 2 cubic feet is about 15 gallons worth and would be roughly 28% of the barrel volume (but I doubt you'll fill the barrel completely full so adjust accordingly).

Before you get your fish, get the media beds online for a few days. The media beds may kick your water temps out of the range you can grow trout at - wouldn't be surprised but they are relatively small so we'll see :dontknow:

Author:  boss [ Jul 30th, '15, 00:03 ]
Post subject:  Re: BioFilter designs?

Thanks Scotty
for the information and links. I just heard from my Wife, they are freeing her from the hospital at Noon. I have been whirlwinding around the house in an attempt to make it not look so much like a workshop and more like the nice clean rooms she has been in for a week. Haha good luck right?

Author:  scotty435 [ Jul 30th, '15, 00:20 ]
Post subject:  Re: BioFilter designs?

Glad to hear they are letting her out, hope the place doesn't look too bad Brian :thumbright:

Author:  Titus [ Jul 30th, '15, 04:24 ]
Post subject:  Re: BioFilter designs?

Brians post on bio filters has prompted me to action. I decided to modify my existing fines filter to an up flow K1 bio filter. With 2 L of K1 media this will be placed immediately after the RFF. In addition to the bio action I am hoping this will also reduce some of the smaller suspended solids. I choose not to add air as where possible I want to use passive oxygenation. Either way open a tap to clean and flush will be easier than hand washing scourer pads.
However in further research I came across the following paper.

I was particularly interested in the section on submerged horizontal flow or raceway flow bio filters.
In my system I have around 1.5 m of 110 mm soil pipe. This holds 10 L of K1. Placed immediately before the sump it is constantly submerged. The media is held in place by gutter guard mesh holders at each end. The inlet has an additional fines filter. My favorite, scourer pads.
What intrigued me was their recommendation to divide the pipe into section.
Each section would then encourage the growth of different bacteria.
Is it worth dividing my filter?
Also without going into long discussions about the relative SSA of different media. Is it a fair assumption that K1 is four times more efficient than clay pebbles? ie my 10 L of K1 is the equivalent of 40 L. Therefore if 40 -50 L of clay pebbles will support two fish 10 L of K1 is an equivalent. 2 *300 grms = 600 1% feed rate 6 grms per day?

PS Good news Brian!

Bio filter B.JPG
Bio filter B.JPG [ 118.22 KiB | Viewed 4092 times ]

Author:  scotty435 [ Jul 30th, '15, 08:42 ]
Post subject:  Re: BioFilter designs?


That first part kind of has me confused. If you're talking about the static up flow filter using K1 then it's really more of a mechanical filter than a bio-filter. Not saying it won't do bio-filtration but it's more geared toward removal of suspended solids. Hopefully you're adding enough DO going in if you're using this as a bio-filter - if you have a way to check the DO at the outflow of the filter I would do this. You'll want to do frequent flushes since under anoxic conditions you'll get de-nitrification.

I believe the zones they talk about in the submerged horizontal flow filter also occur when you have multiple MBBR type filters (or other types in series) with plenty of air and to much organic matter flowing into them. The first filter with the high organic carbon levels encourages the growth of heterotrophic organisms which grow rapidly and overwhelm any nitrifiers. The second filter functions better for nitrification because of the lowered organic carbon (which was used by the heterotrophs in the first filter). So if you're feeding heavily and aren't removing enough organic matter before it passes into the filter, then there is a definite benefit to having multiple sections or multiple filtration compartments where different organisms dominate (a properly designed RFF helps remove about half the solids so it reduces the need for the extra filter section).

I don't know on the last question about clay vs K1. K1 definitely has the ability to support more pounds of fish but it may have less to do with their relative effective surface areas and more to do with the filtration technique since they aren't used the same way and since I never 100% trust the filtration claims :dontknow: Some of the others might have a better handle on this.

Author:  boss [ Jul 30th, '15, 19:30 ]
Post subject:  Re: BioFilter designs?

I just ordered a couple cubic feet of the Kaldnes K2.

Author:  boss [ Jul 30th, '15, 19:39 ]
Post subject:  Re: BioFilter designs?

I just ordered a couple cubic feet of the Kaldnes K2.

Author:  Titus [ Jul 31st, '15, 03:03 ]
Post subject:  Re: BioFilter designs?

OMG! What have I done? :oops:
Confusion leads to hesitation.
Hesitation leads to guessing.
Guessing leads to the dark side........... :upset:
No! My young Jedi. I am your ......

No! Never ever, ever been in Oregon. So we don’t have to worry about that one!
My fault confusing static and moving. :oops:

Thank you Scotty. :flower: :flower:

Author:  scotty435 [ Jul 31st, '15, 05:20 ]
Post subject:  Re: BioFilter designs?

Where's that light saber emoticon when you need it, this will have to do :naughty: ?

Cheers Titus

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