Biological Surface Area in Aquaponics

[@RobsAquaponics]

Thanks for that,.. Really appreciate the clips your releasing as they are helping explain some of the more technical points that are hard to find on forums.. Cheers Chaps..

[@ZipGrowInc]

Nutrient additions beyond the standard pH raising chemicals fall in the sphere of advanced aquaponics. We do occasionally supplement our system, but it's not something we usually recommend for beginners. Unless you're running an agressive commercial aquaponics system, nutrient deficiencies of many of the nutrients you've mentioned are really never an issue. The three big nutrient deficiencies are Fe, Mg, Ca/K (often closely related). Check out the raising pH video for more info.

[@ZipGrowInc]

Hi Rachel, void ratio is only part of the problem - it's the actual size of the voids or pore space that causes problems with sand or pea gravel. That void space in and of itself isn't terrible, it's that the voids (pore space) is very small. That means it captures a lot of organic matter. It's basically the difference between a lot of tiny pipes (pea gravel void space) and one big pipe (crushed granite void space). The solids move through the big pipe a lot easier, thus not as much clogging.

[@ZipGrowInc]

For standard IBCs we usually recommend around 1 pound of fish for every 10 gallons of water. So, for an IBC you'd be looking at between 28-29 pounds of fish total (once the system is mature of course). We recommend around 12 five foot ZipGrow Towers for each IBC. This exceeds the minimum requirement, but it's just a really good ratio of BSA to system volume.

[@ZipGrowInc]

Hi Ryan, Yes, it could be helpful if you're not getting rapid nitrification in your system. Airstones will help with speeding nitrification in some systems, it just depends on whether you have enough oxygen and carbon dioxide dissolved in the water. Typically, if you are cycling really rapidly, you don't need airstones, but if you're having problems, then sometimes they can help. Adding matrix media would basically just increase the BSA of your system, increasing your nitrification capacity.

[@ZipGrowInc]

The SSA of hydroton is slighty more than 3/4 inch crushed granite (70 or so), whereas the SSA of expanded shale is pretty close to around pea gravel (around 85).

[@ZipGrowInc]

Not necessarily, the touching surfaces are relatively small. The SSA's that we list are not computed theoretically, these media types are actually tested in the lab.

[@ZipGrowInc]

Great to hear it worked for you Stew. Sorry for the hassle the first time around!

[@ZipGrowInc]

Shading is the easiest way to reduce the algae. Once the system is established, it will diminish on its own. However, if shading doesn't work, and you don't want to wait until the system is a bit older, you can use a little humic acid to darken your water. Getting your water a healthy "tea color" can reduce the algae significantly by interfering with light. You can find powdered humic acid online. A little humic acid goes a very long way.

[@ZipGrowInc]

Hi RK, if your hydroton is around 70 square feet per cubic foot, 2.95 cubic feet of hydroton would provide around 207 square feet of BSA (70 x 2.95 = 206.5)

[@ZipGrowInc]

You're thinking of a fluidized bed bio filter? Yes, that is correct. The way they're designed is to have high BSA and high void space because you're actually moving the media in the process. They're very good at bio filtration and maintenance requirements are usually relatively high.

[@ZipGrowInc]

It's usually close to a similar sized aggregate, whether crushed granite or gravel. 3/4 Haydite would be similar to crush granite, with maybe 20% more because it's more porous.

[@ZipGrowInc]

Hey Rik, bird netting is decent. We're not entirely sure on the SSA, but it is significantly lower than the SSA of the media we use.

[@ZipGrowInc]

You need to choose the media and figure out how much media you need to provide enough BSA for your system. SSA is measured in a lab and then each media type is rated at a certain SSA. You determine how much BSA you need and do the calculations to figure out how much of the media you need.

[@ZipGrowInc]

960 - Check out the blog post in the "About" section of this video for more detailed info, Russ. Hope that helps!

[@ZipGrowInc]

That's part of it- BSA requirements are based on FCR, fish metabolism, protein content of the feed, protein type, solids removal efficiency, water temperature, nut. availability, DO and CO2 conc., etc. The reality is that most FCRs aren't as great as people hope, and most folks don't use a separate solids filter, they use their growbed, which means there's tons of variation in the amount of solids to be processed, oxidation processes, etc. It's best to plan for the highest possible demand.

[@a12vguru]

Is it better to filter out the solids in like a swirl filter than the grow beds?

[@ZipGrowInc]

That's right Ebrahem. If you remove the plants, the microbial processes will usually continue- you'll just see nutrient accumulation in your water. Now, sometimes there's a loss of efficiency in nitrification/mineralization processes because the roots are a major source of BSA, and when they're removed, some of the BSA is lost. But, if you're using a high SSA media, then you probably won't notice a difference.

[@ccm895]

Not too long ago, I decided to become an engineer. I'm now in a nanoscale engineering program and I just got started with aquaponics as a hobby. Your videos are fantastic! Thank you Sir!

[@ZipGrowInc]

Hi Sean, Yes, basically, the rock in some forms of "lava rock" is relatively basic and will influence your pH, making it difficult to bring it down into the range where your plants will be happiest.

[@ZipGrowInc]

Potentially, Daniel. It mostly depends on the speed that the solids are accumulating at. Even with redworms, I've found that pea gravel ends up being more trouble than it is worth, in the long run.

[@RobsAquaponics]

Great clip, thanks.. Do you have the figures on hydroton/aqua clay Nate ?

[@A-Salt-Life]

Rob Bob's Backyard Farm & Aquaponics Have you gotten the answer to this? I also need the BSA of clay pebbles.

[@GGoffroad2]

5 years later....

[@ZipGrowInc]

Yes that's perfectly fine - just be careful of quantities and make sure you're not over doing it. Using Azomite probably won't hurt, but it probably won't help that much either (unless you're seeing deficiencies).

[@ZipGrowInc]

Hi Sean, Yes, Lava rock is great stuff- excellent SSA, but it can be basic.

[@ZipGrowInc]

The microbes are incredibly diverse so it's really impossible to say since they vary from system to system. They're probably not too much different in DWC systems. The only difference is that the microbes are concentrated in the filtration system, whereas in media based systems, they're concentrated on the media.

[@stevesmith6908]

I do have a question, but first let me say, I am truly enjoying your instruction. Personally, having watched numerous videos on Aquaponics, you are offering the best tutorial I've seen. I realized from an earlier video, the reason that I had set my bacteria levels back, was due to the fact that I had moved all my rock in my system and disturbed a very fragile and fledgling system. Dr Nate, my brother in law and I have built a pretty large initial venture. We have a 3,300 gallon swimming pool, and 5 grow beds. The water leaves the pool and travels through a clarifier and bio-filtration system, then into a media bed. Currently, the media bed is only about 20% full of creek rock, lava rock and clay pebble (I am trying an experiment to see which media seems to work the best and is easiest to work with. . By the way, after the media bed, we have four additional floating raft beds that make up about 72' of length, by 3 1/2' wide and 12" deep. At the end of the system, the water flows into a sump tank, that has a 4,000 gal/hr pump, with a venturi, which recirculates that water into the pool. The pool has about 400 tilapia, from fry (in their own protected cage) to 3" to about 8" tilapia. We also have another basket with about 40 bass and bream. We added them from our pond, just to increase fish waste introduced to the system. My Question: Now that I just watched your video on BSA, more specifically SSA, I was wondering if I were to use the Zipgrow Matrix Medium, how should I incorporate it into our system? Does it go into the Media Bed? Can I, or should I place another media above or below the Zipgrow? Thanks for your help and all the great KZbin videos!

[@ZipGrowInc]

Hey Steve Smith - Thanks for the nice feedback. Would you mind sending this question over to [e-mail]? It's a pretty lengthy one for KZbin!

[@ZipGrowInc]

Thank you! Glad to help the aquaponics community!

[@ZipGrowInc]

That is correct, you got it! We recommend 1 pound for every 8-10 gallons of water stocking density.

[@rjaquaponics9266]

Dr. Nate, I really enjoy your videos especially the ones that demonstrate the science. Many startups are working solely with deep water culture beds. Where are the microbes in DWC systems? Is it only in the bio filters? Personally, I built a 20' geodesic dome in WI and kept it warm all Winter. I have 4 media beds, 4 DWC beds and plenty of room for your grow towers when I can afford them. Rj

[@ZipGrowInc]

Well, that's more of a starting point than a rule of thumb. The primary reason is because many folks both overstock/overfeed, run high temperatures and rely on circulation for aeration. Each design is different. Typically if folks plan systems to run continuously, they can put them on a timer later as they understand their system better. If you really know what you're doing, then the 1 cycle/hr recommendation probably isn't necessary for you.

[@FuellCellScientist]

Another great video! My apologies if this information is elsewhere but what is the media volume of the 3′ and 5′ ZipGrow Towers (or rather, what is the BSA/tower)? I’m trying to get a feel for the number of towers/gallon needed with ~10g/lb.-fish. Cheers and keep up the awesome work.

[@ZipGrowInc]

Magnesium is occasionally deficient, and can be treated with epsom salts. Mn is seldom deficient. Mo is almost never deficient. These nutrients are micronutrients necessary in only small quantities, and fish waste provides more than enough of these nutrients for plant metabolism. If you're really concerned about it, you can use seaweed extracts to supplement these nutrients.

[@rkulberg]

Can you comment on why it is a rule of thumb that one full volume of fish water needs to cycle through the plant beds every hour. Seems to me that fish aren't releasing ammonia and solids every hour (and instead only 1-2 hours after they eat) so you may be able to save on electricity if you flood less often. The plants roots themselves don't necessarily need to be bathed in water every hour as long as the media retains enough water to keep them moist. Aeration of fish tank could occur separately

[@DanDannyDanielleBob]

Thanks for the video. If i am understanding your lesson correctly, is it safe to say that the benefits of a moving bed filter is to utilize a media with a high surface area, while increasing the 'effective' void ratio of the media? Effectively you would be getting a higher BSA in a lower volume filter, and lowering the build up of solids by keeping the media moving? Are there any other reasons to use one?

[@AmerijamAcres]

Does adding as bio filter help for deep water culture systems? Should the size of that filter be adjusted to the size of fish or is it better to add a media bed to compensate?

[@narfman11]

Hi Nate, Thanks for the vids. They are inspiring. I am design a small system for testing currently. So far a simple loop, with a tank, sump and a couple makeshift drip towers. (I may purchase yours if I find it in my budget.) I am writing to request a video about pest control though. Currently I am working to populate the surrounding garden with plants for beneficial insects. I suspect this is insufficient and I am wondering what else I could consider for an organic system. Cheers

[@ZipGrowInc]

It depends on the size. Most of our towers are around 30 square feet of BSA per linear foot of tower.

[@alt1964]

In the video you mention 100 sqft BSA / pound of fish as a recommendation, I am using a 330 gallon IBC and want to stock it with tilapia, how many fish do you recommend I have in the tank and how many 5 foot zipgrow towers will I need?

[@justgivemethetruth]

fantastic and very informative video!

[@ZipGrowInc]

Yes, you got it. Good luck.

[@rkulberg]

I am a little confused about the numbers you have for sand- why is the void ratio 40% if it is so tightly packed and why is pea gravel a bad substrate if the SSA is 85, is it because it has such a low void ratio that it makes it undesirable? Thanks for this info!

[@6781spirit]

Helped me alot! Thanks

[@ZipGrowInc]

Glad to hear it!

[@rkulberg]

Thanks for answering my question! I was also wondering if you would comment on the importance of the CEC property of the media. Seems to me that in a Flood and Drain you may want a high CEC since the roots aren't being constantly bathed in the nutrient rich water and retention of nutrients near the plant zone may be beneficial. Also, a high CEC property may allow you to get away with fewer or shorter flood cycle. What do you think?

[@94566rik]

At the aquaponics conference last September on the farm tour Colorado Aquaponics was using bird netting in their de-gasing tank. Has the SSA been worked out or known for bird netting? Thanks rik

[@quinnthompsontv]

OK, thanks for the info. Since my system is already setup and i really don't have the room to add another fish tank. Would it be safe to go with the 6-7 lbs of fish/goldfish? Fish Tank: 72-75 gallon fish tank. Grow Bed (pea gravel 3/8") = 16.14 FC (10" high X 93" long X 30" wide approximately) Thanks again!

[@ZipGrowInc]

Also, because of the stocking requirements, you'll need around 500 gallons of water to do that (so your tank is inadequate). Remember there are a lot of different variables at play here.

[@rkulberg]

Thanks Nate! I read that each square meter of biologically active surface can metabolize nearly one gram of ammonia per day. If this is true then 1 lb of fish would only require a minimum BSA of 2, not 25? My calculations: 1 lb Tilapia produces 0.2 grams of ammonia per day. If 1 sq meter of BSA metabolizes 1 gram ammonia/day then 0.2 grams of ammonia would only require 2 sq ft of BSA (0.2 sq meters). Why is the min BSA 25 sq ft/lb fish with a maximum set at 100 instead of 2sq ft/ lb Tilapia?

[@ebrahim.ahmed.411]

I Do Have a Question Dr. Storey. Do we use the Surface Area Just for nitrification and mineralization?? and if the plant went missing the same process will go on with no issues other than the accumulation of nutrients ??

[@narfman11]

Another inquiry: Is it safe or useful to add something like Azomite or compost tea or sea minerals into an aquaponics system? I would prefer to reduce the amount of synthetic or extracted chemicals as much as possible.

[@Naut1188]

thanks, I did not know that. Is it a continuous leaching of basic compounds? I normally think of ceramic-like materials as being pretty inert.

[@sinisaveir]

Hello, any numbers for SSA for expanded clay? I am planning to start the system with the expanded clay as media... Thank you in advance for your answer.

[@olyloleah]

how do you get potassium, phosphorus and micronutrients in general in your system ? so far i have only found apatite rocks and potassium feldspar for my P and K but i'm looking to get a steady amount of manganese and magnesium to accelerate metabolizing nitrogen, i'm wondering if you guys are doing anything like that ?

[@ZipGrowInc]

You're quite welcome!

[@Ryan-lh3xl]

Dr. Storey, Thank you for all the great information. I just wish I had it 5 months ago. I am in the adding ammonia/waiting for nitrites to show phase. Would I get any benefit from adding your matrix media into a 55 gal drum and running water from my 200 gal fish tank and then from the drum into the sump tank? Would air stones added to the drum help or would it all be a waste of time and money?

[@keithnewlin4584]

What is the SSA of coir? Does it matter as much in a periodic flood system?

[@jesusrubio966]

I have some troubles with microalgae bloom in my aquaponic system, I guess microalgae compete with plants for the nutrients. ¿what can I do to pass through this bad situation and reduce the amount of microalgae? I have installed a home-made biofilter with sinthetic fibers and anti-mosquito net, but I seems to be not sufficient to filter the microalgae. Any idea will be useful. Thanks

[@rkulberg]

ammonia calculations: Tilapia eat 0.015 lbs of feed (i.e. 1.5% of their body weight/day) which will produce 0.2 g (or 0.00045lbs) of ammonia/day (i.e. 3% of the feed is converted to ammonia or 10% of the protein in a 30% protein diet). Also, seems that the BSA requirement will change depending on the fish and the amount of ammonia it produces per unit weight? for instance, goldfish will produce ~3x the waste per unit weight as Tilapia so will they need more BSA per lb than Tilapia ???

[@ZipGrowInc]

So that's the minimum, but your tank size is insufficient. The max amount of fish biomass your system could support at system maturity would be around 55 pounds assuming you had a 550 gallon fish tank. Pea gravel will foul fairly quickly and you'll lose most of your BSA when that happens. At maturity (about a year into production), you could take your stocking density up to around 50 pounds of fish.

[@Naut1188]

Any comment on lava rock? I've been using lava rock in my sump filters for the bio-filtration, years before I even knew about Aquaponics. Now I use it in my aquaponic systems.

[@ZipGrowInc]

We have a video about pest controls on the way! We're also putting together another ebook on how to calculate application rates in aquaponics systems. Keep on the look out for that soon!

[@justgivemethetruth]

is the specific surface area computed theoretically, and does it take into the account and minus the surfaces that are touching/tangent .... for instance any grain of sand is probably touching other neighboring grains of sand a high percentage, so is that dead area accounted for in some way?

[@ZipGrowInc]

Hi enigma, you can find ZipGrows on our store for $67. Not sure where you're seeing $80. And feel free to reach out to our other growers and customers, the value is way, way, way higher than $67 when it comes to how much high quality, nutritious produce you can grow. If you're growing food for your family or as a small business, you'll be absolutely amazed at how fast you can recoup that investment also. We've know they'll work great for you too!

[@ZipGrowInc]

Sand is poor because while the void ratio is good, but the pore space is very small- essentially there's quite a bit of room between grains of sand, but because the particle size is so small, the pore space is small.

[@danielperry2153]

Dr. Storey, Would the using river pea gravel be okay with the introduction of worms to help consume solids?

[@justgivemethetruth]

I understand how the requirement works, but I asked you how they measure SSA? Do you know or not?

[@justgivemethetruth]

Thanks Nate ... that's kind of what I said - experimentally relate a volume to a surface area.

[@kevingubbels]

does having the media in a MBBR help lower the ssa you need?

[@stephenbutler2437]

According to Nate's later calculations (in comments) its approx.1' of zip towers for each 5 gallons of water or approx. 2' per pound of fish in a mature setup.

[@ZipGrowInc]

A 5 foot tower will take 1.5-2.5 pounds of fish per tower, Stephen Butler.

[@byronwooten5092]

Bright Agrotech Do you mean it requires 1.5-2.5 lbs or that it can handle up to 2.5 lbs?

[@ZipGrowInc]

Yes Byron Wooten - Each 5' tower will handle 1.5-2.5 pounds of fish. This is the equivalent of 0.3 to 0.5 pounds of fish per linear foot of tower.

[@terrenceroach9398]

I have a DWC system...an ibc tank for the fish.a solid waste filter, a bio filter with K1 media, (3) 4ft×12ft ×10inches grow beds...I have over 500 spaces for 2inch net cups....how many fish should I have for my system?...

[@ZipGrowInc]

Hey Terrence, this is a great reference: university.upstartfarmers.com/blog/reference-guide-aquaponic

[@HeavyDemir]

I ponder :) if your system uses 100% of available nitrates in on cycle wont that starve your plants as all available nutrients have been soaked up ? Pls help me understand.

[@bolavenfarms222]

Hello Nate, could you share if charcoal or bicchar would work well bio medium, with higher SSA and void ration? thanks.

[@Borkith]

2.5 sq ft of SA / Gal minimum, 10 sq ft of SA / Gal recommended. 25 sq ft of SA / lb fish min, 100 sq ft of SA / lb fish recommended. That's 10 gallons per pound of fish, am I understanding that correctly?

[@asifshakur1185]

Can we use LAVA ROCK as bio media? what would be the sq footage for it also. thanks

[@knightnvy]

is it practical to just add media to the sump?

[@justgivemethetruth]

OK, then how do you think the SSA is determined?

[@jaunbeetge7005]

Hi Nate. Jaun here from South Africa. Thanks for the video. Hope you can help. Ive set up a 16500 liter DWC system (17m x 1,8m) with a 18 meter NFT. My fish tank is 6000 liters and can hold 150 koi fish (40 liter per fish) that I want to grow out to 500g. My question is, how much bio media (K1) do I need to process the waste of the 150 fish, I will be feeding them 1,5 % - 2% of their body weight?

[@captaintim38]

Professor, once again excellent job!!

[@ZipGrowInc]

It depends entirely on the size of the media- for the 1/2 inch sized stuff, I'd figure on your SSA being around that of 3/4 inch crushed granite.

[@justgivemethetruth]

It sounds like you do not really know if you cannot give a quick executive summary of how that number is derived. I'd guess it has to be a statistically derived number, perhaps by measuring some biological residue from an experimental run where surface area is connected to volume in some way.

[@RKCastillo]

Hey Nate...Great video, as usual! I'm trying to see if I did my math correctly. I have a small 50 gallon fish tank and two media beds that are 25"x17"x6' which is 2550" cubic inches or 1.47 cubic feet (hope I did that correctly?) So, the 2 beds equal out to 2.95 cubic feet. I'm using Hydroton which is about 70. This is where my math gets screwed up. Were your numbers for square ft or cubic feet? Are my 2 beds enough for the 50 gallon tank?

[@mikeman230]

I have looked all over and checked with the manufacturer with no luck. Would you know the SSA of HYDROCORN expanded clay pellets. Thanks for getting me started in aquaplonics

[@WittyRat]

Mike Man If you are looking for the original name brand, it doesn't exist anymore. The mine ran dry in Germany. Just look up expanded clay and you'll find the same stuff made in different areas. Works the same as the original.Cheaper too for the most part.

[@TheDrMash]

Hi Nate. Can you explain on, how to calculate this for DWC system? Many thanks

[@ぷらしっ]

What are the bsa of bioballs?

[@XRPSAINT]

Could you look at expanded clay and let me know what the specific area per cubic feet is please? Thank you so much!!

[@a12vguru]

So for the BSA is it square feet or the cubic square feet?

[@chadpace36912]

Is there a formula for the BSA of zipgrow towers versus feed rates?

[@MultiIncredulo]

Thank you Nate, for your videos, really interesting scientific explanation, although quite difficult to pass all these American measure units to European units of measure.

[@BobCampbell530]

Can you provide a link to your SSA specifications?

[@scottsgonehunting]

Love your videos!!!! I like how you have a PHD and back up your teaching with the academic and technical specifics. I have been playing around with this stuff for years and still have learned a lot since I stumbled onto your videos.

[@ZipGrowInc]

Thanks scottsgonehunting !

[@lapfungleung5879]

I am wondering where are the paper or article taking about BSA from?

[@quinnthompsontv]

Hi, I've watched this video a few times and wanted to make sure i really understand the calculations. Could you please take a look at my numbers and let me know if i've calculated correctly? Pea gravel media = 85 SSA, Bed = 16.14 FC, Fish Tank = 72 gallons, Goldfish Based on your chart... 85 SSA / 25 BSA = 3.4 LBS of fish 3.4LBS of fish X 16.14 CF of media = 54.88 LBS of fish - is that right? This seams like an awful lot of goldfish!!!

[@superhoodc]

It would be ten cubic feet of your media to cover 25 lbs of fish at 100 sq foot a pound correct? 100 x 25 is 2500 sq feet of surface area by 260 sq foot would be close to ten.

[@weathergenerator]

how do we know the time needed for treating a certain volume of water through the mediums.

[@chelseamccrary3044]

So, I am really interested in obtaining the zipgrow towers, but I would love to know the data on how many fish can live on one tower, once the microbials are in tune with the system. I am new to aquaponics, and want to build my own system, but I'm still in the research stage on what I want and how to set it up. I really love the zipgrow system, but want a little more data to back up the expense (say.... vs. a regular horizontal system). I would love to fine tune my system for my family and loved ones first, but have local mom and pop restaurants that would love to buy fresh off of my production when possible......thoughts? advice?

[@CharlesLabedz]

hm whats the ssa of Haydite?

[@ZipGrowInc]

Specific surface area is always in square feet per cubic foot.

[@sulaimanhaiderseddique3590]

Assalamu-Alaiqum bro, many many thanks for your Dedication and Contribution to teach us about Aquaponics. But I'm looking for some specific information about MBBR, specially MBBR surface area calculation for g or oz of fish feed. Have you any suggestion for me!

[@tonkatoytruck]

Do you have any numbers for BioBall media?

[@mdberkarslan]

You are the king👑👑

[@ZipGrowInc]

+Mehmet Berk Arslan No kings here! Just trying to share what we know. Thanks for tuning in!

[@asterio8405]

Hi Dr Nate...Is there a kind of chart where you can get the SSA values and the void ratios of the different types of media or you figured them out? would be nice to know how to estimate them in case you want to work with a different type of media not described anywhere. About the numbers, we are working with 25 fish (25 pounds) and the minimum BSA of 25 sqft per pound of fish. Then you use the SSA of 50 and you get that SSA supporting 2 pounds of fish per cubic foot, i guess you get that using the BSA that tell us that 25sqft of media are needed per Pound of fish. Basically you multiplied the BSA of 25 times 2 to get those 2 pounds, but I don't understand why since BSA and SSA are not the same. Having that, you get the 12 cubic feet of that type of media dividing the 25 fish (or 25 pounds) by the 2 fish or pounds a cubic feet of that media can support = 12.5 cubic feet. Too bad you didn't write that up. I got lost on that part. It seems that you are using the SSA as BSA to get the amount of fish you get per cubic foot. I don't understand that. I hope you have a chance to make another video giving another example. Anyways , thanks a lot for sharing this info!!!

[@needlepro]

So how many ft2 SSA in a zip grow tower??