I started my first RAS build this weekend. I'm going to be taking my time and taking lots of pictures. I will update this thread with the pictures and progress as time allows.

At some point, many of you will probably read this thread and ask why did he take so much time on X. The answer, I was raised by a machinist and overkill is all I know.

Things I've learned thus far:
*If you can find used barrels that were used for food grade ethanol get them! (nothing easier to clean out of a barrel than ethanol).
*Using a cutting wheel on a dremel or small air grinder with lots of patience makes much nicer cuts than a sawzall.
*Using a knife to rasp/chamfor the edges of cuts into the barrels works well.
*A 7x7 sheet of deer netting makes a nice sack to hold the remaining 93x7 sheet of netting bunched up. Simply take the 7x7 sheet and lay it centered over your topless barrel and stuff the netting in. Then twist, tie and melt the 4 corners of the 7x7 like you would the end of a rope and form it into a handle (pictures of this to come).
*Purchase your pump before you think about buying PVC fitting so you know what you are working with.

The design I am planning, is to use 3 barrels laid on their sides for the fish and one barrel standing up packed with deer netting for the bio filter.

That's all for now.

If anyone has any suggestions, ideas or anything feel free to fill the thread with your thoughts and I will take them all into consideration during the build. I still haven't decided on the pump or the aerator that I will be using for this. Your thoughts on this this are welcome as well.

I will try to upload the first pictures from last weekend tomorrow. There probably won't be any new action until this weekend when I have more free time.

I look forward to your feedback and input throughout the project.

I've been digging around all night and researching. I think I would like to get some matala (or hvac filter pads) as a pre-filter.
http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=15799

Does anyone think this would be worth it. My range of thinking had gone form "I NEED ONE OF EACH!!!!!11oneoneoneeleven" to "I don't need these at all."

At this time, I'm thinking I want to have some pre-filter media but nothing crazy.

I think I might just get 1 or 2 of these for 8 bucks each:
http://www.homedepot.com/h_d1/N-5yc1v/R-...p;storeId=10051

Thanks in advance for your input. I'm going to go load the pictures I took so far as promised. I promise the next week will be more exciting.

As promised:

Well if i had some input I'd give you it, but i honestly know nothing about RAS systems.. I'm interested and will follow the thread though.. Good luck and keep the pics and info coming..

You are going to need a solids filter (pre-filter) otherwise your biofilter won't be worth anything. Some of the pond filter systems out there are not very well suited for RAS because the fish and waste are not concentrated and the pond's biological process takes care of it's share of the process.

A bag filter would be a good choice for something simple and cheap. Plus you can clean them easily for reuse. They will eventually become particulate laden, but they are cheap.

What fish are you planning on?

The fish I am planning on having are RES, PS, & BG.

How big are these fish, and how many?

I don't have the fish yet, I am just working on the system first. The plan is to have about 5-10 of each RES, BG, and PS sunfish. The plan is to get them at smaller size and raise them to breeding size to eventually experiment with cross breeding them.

DMRBG,

I use the above filter material for a suspended and settleable solids filter in my systems. I don't bag it like you did as it's easier to clean with a garden hose and nozzle if you cut it into pieces. I clean the solids off daily and do a 10 percent water change daily due to the several hundred bluegill and yellow perch in my two tanks. I also use a bottom drain for settleable solids, which works really, really, well. When I pull a gate valve to purge the bottom solids -- before they go down the drain --it's like nasty smelling black coffee coming up. *

Clarifier tank (where the mesh filter goes into) minus the fish tank



I use a homemade RBC for a biofilter, but a simpler and cheaper biofilter would be to use a 55 gallon drum half filled with plastic media, an inlet and outlet for water, and a diffuser on the bottom. The water would overflow via gravity back into the tank if you position the biofilter above your fish tank.

An RBC inside a fish tank which is the way I had it originally. I no longer use an agitator and the entire system that has a 200 pound capacity can be run on 39 watts of electricity.



I've since moved my RBC's to a separate tank here:





I would strongly suggest cycling your system before adding the fish. Cycling with fish is very risky and hard on the fish. You could easily kill your fish.

Find you a circular stock tank at Rural King, TSC or similar store (preferably plastic) vs. a 55 gallon drum. A drum would be a stressful place for fish and severely limit your lbs. per gallon.

I'd be happy to share a diagram of my system if you're interested. I also have free coupons for the book Small Scale Aquaculture by Dr. Steve VanGorder that is coming out in print soon. (2nd Edition) If you use the coupon you can get it for $16.00 vs. a higher price later. PM. me with your snail mail if you want me to send you one. I get nothing out of giving away the coupons which were given to me by the author. Just the satisfaction of knowing the best book on small scale systems is being made available at an affordable price.

* I'll be using the solid waste water for our raised garden this year, and will be setting up an aquaponics fish tank ans system outside in a month or so. I'll probably be raising tilapia for food in that one.

Fantastic read, keep it coming!!

Thank you for the information Cecil. I was planning on looking into larger tanks in the future; I wanted to start small and cheap so I was planning to use (3) 55 gals(on their side for more horizontal surface area than if they were standing and keep the stocking density low). I definitely plan on cycling the system for a long time before any fish are added. I will be using filter media from my aquarium that has a pet sunfish in it to kick start the bacteria (supplemented with some feed in the water). I got the coupon that you mailed me about a week ago and mailed it in with a check. Do you know when the books will be coming out?

At a density of 6 small sunfish per barrel on its side do you still think the stress would be high? Perhaps I should just go straight to the stock tank rather than taking baby steps and upgrading as the fish get larger. This will be interesting, I don't think the wife realizes this is going in the basement yet.

Just a small photo update. Some cut up light diffuser panels and furnace filter, 2 notches in the barrel to allow for greater diameter pieces to fit inside and a bonus photo, the helper.

I love this type of stuff!

I am glad more people are getting involved with Recycle Systems.

Your barrel system will work quite well for FHM.

I'm glad you are enjoying it. I will be sure to give updates as frequent as possible all the way through having fish in there.

Man I responded to your questions DMRBG but lost it somehow.

Here goes again.

Not sure when the book will be out but it should be any time now. I know it was at the printers a few weeks ago. Steve is an honorable guy; no worries.

I think a half barrel would be fine for six small bluegills

I like the circular tanks because you can get a centripetal flow going that moves all settleable solids to the center drain.

BTW I love the cat. He looks like he wants you to pay attention to him or her. Tells us about the cat.

Looks like a main coon, he's dreaming about fish jumping out of the barrel.

Thank you for your reply Cecil. The cat is a female Siberian cat named Crash (her feet are furry and she had a tendency to crash into things when she was little) and she acts more like a dog than a cat. She sits on command and follows me around.

Edit @ pond: She does watch the sunfish I have in an aquarium and plot his demise.

So cool! I love both cats and dogs which I've heard is not common. Supposedly it's usually one or the other. My twin brother has a cat that looks like Garfield and acts like him too!

Here is a 4 barrel gizmo I was going to whip up for FHM.

Pretty simple.
2x6 frame sitting on cement blocks. 55 gallon drums with 30 gallon filters.
I did the layout so I could build the frame easily.

I still may do it in the future, but I have to complete my current project.

JKB,

Do the fatheads need live feed when their yolk sacs are depleted or do they go on artificial feed right away?

They will go on artificial feed right away if they can get it into their mouth. They are actually mini eating machines and are not fussy at all.

Obviously, there is more to it than some barrels.

I may just do a project on this. It would be relatively easy to integrate without costing much. I'll think about it.

It would be great if some of us could get some parallel projects going. FHM would be would be a good starting point, then build on up thru the food chain!

JKB,

If they go on feed right away the only problem I would see is keeping them out of the drain but removing waste efficiently at the same time.

DMRBG asked for a diagram of my improved system over the original one in Van Gorders book. I thought I'd post it here in case anyone else can use it.

Sorry about the "on a napkin look" but that's the way I operate.

The first pic is the system set up in a local high school with the RBC on the opposite side of the fish tank than in the diagram. The u tube siphon is not show in the following pic nor in the diagrams. It simply sits in the clarifier tank and the fish tank.




This is the fish system including center drain, clarifier, and RBC in a seperate tank.




This is a diagram of the homemade spray bar that provides the centripedal flow that moves the settleable solids to the center drain. The diffuser also aids in this and provides oxygen. This spray bar runs off of the same 30 watt pump that runs the system. The only pump btw.



Here's a u-tube siphon in use on my very first set up. Notice it in the clarifer tank and the fish tank. This was when I used another u-tube siphon to run water back to the fish tank. I now set the RBC tank above the fish tank and run the water back via gravity.



If you have any question feel free to ask. If you have a WT* attitude keep your mouth shut.

That is why I mentioned that there is more to it than barrels

Good Luck on your RAS set-up and experimenting with cross breeding, I have PS's that I've been selectivly breeding for 2 years hoping to increase their growth rate.
Don't forget to get a good chemical test kit and a PH test meter is inexpensive and a quick way to monitor PH.

Thank you for the encouragement and information. Have you been enjoying your selective breeding experiments? I hope they are fruitful for you.

It's been interesting, hopefully my selected offspring from 2010 with spawn some fast growers this summer, maybe I'll live long enough to see good results.
I didn't make the filter for my RAS, I was lucky enough to find a used bubble bead filter from someone who was getting a bigger one for their Koi pond. Craigs list comes in handy.

You guys are doing some impressive stuff.

AP. Is the RAS just for holding them over? Or, are you breeding them in tank?

The RAS is just for the cold months, Oct. thru April, they go out to the backyard mini pond in May where I have small spawning tubs filled with sand and gravel for them.
I also have weighted pvc pipes with artificial garland attached to give the fry some cover.

Oh it's another one of your "secrets" right?

Not a secret, just common sense.

You simply put an insert, like one of those deep fryer baskets that they make french fries in, except it is a tighter mesh into one of the barrels where all the Love is happening. After several weeks, dump them into another barrel and let them grow, then start again.

You are not the best plumber, so I am sure all of your standing stock would be sucked out the bottom! Just kidding!

I guess you haven't personally experienced the frustration of small mesh just fine for keeping the fry in but also the solids and quickly clogging the fine mesh due to the tremendous amount the fry eat and expel. This can lead to bacterial gill disease or worse D.O. and ammonia issues. I've already found some things look good on paper but in practice can be otherwise.

No, plumbing is not my forte, but I get by.

You should be OK with a 1000 to 1500 micron stainless mesh.

Solid sides with perforated sheet for the bottom would also work. It will help in keeping the feed suspended longer with a diffuser under the insert. You would need to perforate or screen the top for outflow. Good idea, just how much flow is needed? Got me hanging! Maybe a combo of lightly perforated sides and a hole filled bottom.
Sounds like a WE feed training rig to me

I made such a basket out of 50 micron filter material. That was not a good choice, but was just testing. The water inside obviously got dirty, while the water outside was pretty polished and clean. Hey, I had the stuff and thought I would give it a try. It's OK for a couple of days, and that is about it.

I also made one from vinyl coated aluminum window screen, and that worked. Not much buildup to speak of. I did not spend the time and make a wire frame for it, so it was kinda flimsy. Just experiments. Duct tape was also employed.

There is a lot more to this. The barrel rig should work just fine.

"On Paper", I call them Cartoon's, because sometimes they are funny

Anyway, enjoy your projects!

None of us think the same way, and that is beneficial to everyone!

Speaking of stainless steel mesh. Has anyone here made anything like one of these?

http://www.newenglandkoi.com/Cetus-Sieve/Cetus-Sieve-Gravity-Fed-p-494.html

They are stupidly expensive but from what I can tell they are about as good (easy) as it gets for low maintenance solids removal. I was thinking about getting some 200-300 micron screen and making something like that to strip the solids before the water goes into the bio-filter.

Thoughts?

Edit:
I first saw the sieve in this video http://www.youtube.com/watch?v=hS3UdYphk9I&feature=related

This guy has a pretty wild setup. Far more elaborate than I am planning.

You would be stupidly wasting your money!

This solids filter was originally invented in Germany when the Big RAS, Hey just throw fish in water boom was happening.

I am surprised it actually survived, but this seems to be a much smaller knockoff. AES use to sell the originals. I see they have a few models for Koi ponds. Looks like they found a market.

200 to 300 microns - were going back a very long time!

Filter techniques for aquaculture have advanced a bit in the past 20 years. Tilapia can tolerate poorer water quality than most other fish, therefore better filtration is needed for other species.

I'm not sure I'm following. Why would it be a bad idea to screen the larger particles out before going into the main filters? I expect it would decrease the frequency with which you would have to clean the main filter media.

Sorry if these are stupid questions... I just saw it in action and though; Wow, that would be easier to clean than the filter media inside of a barrel (hopefully effectively decreasing the frequency with which the barrel filter must be torn apart and sprayed out).

Edit: Just to be clear, I would never spend a grand on a glorified screen and barrel but I would be willing to make one with some cheaper nylon mesh, barrel, Lexan, and aquarium silicon for $150-200 or so if it made the system more maintainable.

Edit2: While his design has some flaws, I can appreciate the cleanliness of his fabrication. I don't know why he is using aquariums which are probably about the most expensive kind of tank you can get but I like his use of IBCs which is something I have been considering as well.

What are the main filters?

All I saw was some wadded up netting wrapped into a ball as a biofilter. Ain't gonna happen! No Way, No How!

You will eventually get it

It is your world to experience and enjoy.

All anyone can offer is a few foot steps.

I am not trying to be rude so please excuse me if it comes across as such.

What I am seeing is fragments of thoughts and not guidance or footsteps...

As far as what you see... What you see in my photos (if that's what you are taking pot shots at) are the very beginnings of a clarifier with some bio filtration capabilities that are modeled after Cecil's system which has already proven its self and is by no means intended to be the sole means of filtration. If you look through the rest of the thread again you can see more information on Cecil's system that included a RBC which is also used. If you look even further you will see that my total fish weight is intended to be extremely low (18 or so medium sunfish).

Cecil is already using a variation of this system to filter a much larger tank with many more fish without the extra solids screen (to my knowledge he is not using one) which I am thinking about adding for the convenience of not having to spray out the mesh as frequently which I believe will also help maintain a more stable beneficial bacteria population.

So... Please explain your comment to me because I fail to see how adding a solids screen to a proven method takes it from proven to "Ain't gonna happen! No Way, No How!".

On an important side note:

I would very much like to keep the tone of this thread positive, constructive and educational. Please try to keep with that spirit while posting.

Thank you.

Likewise DMRBG and I think we are doing O.K. so far. You have to understand JKB is an engineer and I think he is just humoring you. He does that me all the time! Engineers always think they are the smartest people in the room and they usually are.

Just remind him when you get fish in your system that yours is no longer a idea in your head. Believe me there is a difference. Even in the finest designed systems Murphy's Law applies. And although it's a trite expression, the more complicated a system is the more things that can go wrong really applies to RAS'. At a recent aquaculture meeting Dr. VanGorder was telling us about some of the most expensive and well designed systems he has seen that ended almost as soon as they started.

I'm no engineer and my philosophy is the KISS principal. My system is not complex, but it gets the job done for what it's designed for, which is bringing in fish for the winter to get a few more inches on them.

Please direct any questions you have to me and I'll be happy to answer them the best I can. However I must warn you I am still learning, but I'm having a blast doing so.

Hey, you want me to cross-examine him?!

Oh I forgot lawyers can convince people they are the smartest in the room!

Nah no need to.

Well, we may not be able to convince people we're the smartest, but we are often successful at making others look like they're the dumbest! (Just messin'!)

Oh no, all the people I know that are lawyers, including a girl I dated that graduated Harvard Law are smart cookies. Eric is no dummy and of course you're not. Myself, not sure I could have made it through law school. Same goes for med school.

Some can make the grade, but like any profession, there are exceptions! You don't give yourself enough credit, my friend.

I am sorry, I must have missed something. The way it read was that the deer netting was your biofilter. Cecil uses his deer netting as a pre filter. Big difference. 200 to 300 microns going into a submerged static biofilter is not the best plan. You will want to tighten that up a bit. I suggested a simple bag filter as a pre filter. I would choose that over the netting, why? they are cost effective, simple and work. You can get them in any micron rating and they come in many FDA compliant flavors. Plus, they are easy to clean.

HVAC filters often contain unwanted chemicals such as fire retardants. Be careful if you select one of them.

Microscreen filters are a great thing. Depends on how much money you want to spend, not just on components, but operational costs as well.

Back in the 90's, everybody and their brothers were out to invent a better mouse trap. Some of the stuff was pretty neat, a lot of it was also impractical or it never worked and was actually sold to consumers. I especially liked one companies take on fish harvesting. The tanks were circular and had a liner. When you wanted to harvest or grade your fish, you simply pumped air under the liner. It blew up like a balloon and all the water and fish were directed into a channel. I wonder how many times you could blow one up before a failure occurred.

Many books were written. A lot of them are no longer in print.

The book Cecil mentioned by Steve VanGorder is a very good one. Simple and practical.

It sure would be interesting to hear the whole story about a new fish hatchery that was built in Alaska. I was talking to an employee there and they were a bit nervous because things were not going as smoothly as promised.

That is true, however I did make one lawyer look stupid in front of a circuit court judge. I don't think he did his homework relating to UL listing and field labeling requirements for equipment installations.

Very true Cecil. Nothing like having your system up and running with fish present.

Many a fish farm bit the dust when they adapted RAS technology. One of the prevailing reasons according to Timmons, is that they just did not understand the technology they bought in to. Many other reasons to do with economics also. If you are just on the edge of making a profit and the utility companies hike your rate, so long!

My stuff is not overly complicated. Pretty basic really, except my future fish will be able to send me text messages

DMRGB:
Here is some sunfish info. You can download it free: Sunfish Culture Guide

Sorry for getting so defensive yesterday... You know how it is when you put your ideas/plans out there.

Thank you for the sunfish culture guide link, I will read that today. The information about the HVAC filter containing flame retardant chemicals is also appreciated. I knew there was a possibility that the filter would contain anti-fungals/anti-microbials however I had not considered more volatile/harmful additives that might still be left after several dish soap soaking/rinsing cycles.

It appears that we have the same opinion of the screen pre-filters. They are nice but way too expensive. I've found 200 micron nylon mesh for cheap but unlike the more rigid stainless steel mesh, it would have to be supported with pllexiglass rails or something similar. I'm still working it out but, if it can be done for reasonably cheap, I'd really like to be able to strip out the larger solids before it goes to the clarifier.

I also wanted to let you know that I am doing this purely for fun and it is just a hobby, I have no illusions about turning a profit with this little experiment.

I assume you meant you have no illusions about turning a profit with this little experiment? If so, I have to warn you this stuff is addictive. It combines fishy stuff, tinkering, and bringing the fish in right close to home for observation, which really hooks in a lot of people.

I have illusions all the time, but I try to stay grounded in reality, if I stray my wife brings me back.

It really is fun to experiment with fish production and cross breeding, especially if you get good results, have fun with it.

Here's some info on different systems if you haven't already seen it.
https://srac.tamu.edu/index.cfm/event/getFactSheet/whichfactsheet/104/

Good catch. I did miss the word "no".
edited and fixed

Thank you very much for this link. I haven't finished reading it yet but I am enjoying it very much so far. This is a must read for anyone planning on crossing sunfish.

Thanks again!

Edit: I got a chance to finish it and looked through a couple of other articles that had information on sunfish hybrids.

I've found more information on sunfish x LMB hybrids than I have on PS x RES hybrids. There is virtually no information on PS x RES crosses even though (as I understand it) they are very close genetically.

Hopefully phase II of this little plan; to make a cold tolerant snail eating machine won't be a complete failure.

No need for an apology. I was being a bit unusual yesterday.

There is some interesting information on this link: NCRAC Worth your while to check out.

A word of caution on the Parabolic screen filters. The geometry has to be quite precise, and they use a very special mesh weave. I have not tried to source any material because they can't filter down tight enough for RAS applications. That is why they were a bust. Rotary drum filters are pretty much the choice in the microscreen department.

Cecil has a link to a small unit, if he would post it.

Patience! This project of yours will not show results very quickly. Think in terms of years!

Some research scientist may have the info you are looking for. Could also be bubba who never finished the first grade. You may even have to do it all by yourself!

The point is, This is not a Plug-n-play, instant satisfaction, got 400 channels, why do I get so many text messages, fast and unhealthy food thing!

It is gonna take some time

And to add to what JKB is saying with those king of micron tolerances you almost might as well go with settling tanks.

Here's are a couple of links to a couple of rotary screens that are less costly than the high end commercial ones, but still not cheap.

http://www.koiacres.com/koi-acres-products/rotary-drum-filter.html

http://www.aquatechmfg.com/Rotary%20drum%20filter.html

I've also never seen info on the ability of PS's and RES to cross, mainly either one crossing with BG.
Any of the resident fish biologist's have any info?

Redears hybridize with bluegills fairly frequently in some of the natural lakes in my region. I've also seen pumpkinseeds hybridize with bluegills. I've never seen a redear hybridize with a pumpkinseed, but maybe i wouldn't recognize if if I saw it?

Classic illustration of why one should never ask a question to which one doesn't already know the answer when examining a witness! I'm sure you did it with real style, too!

This is why it costs so much to retain a Lawyer, they keep asking questions they already know the answer to while the meter is running.

You're on to me!

centrarchid on the nanfa.org forums has crossed RES with PS and back crossed that with RES ((RES x PS) x RES) and from what I read the offspring are quite fertile (which is actually desirable for my experiment and undesirable for his). I have sent him a PM on those forums to pump him for information; I am hopeful but I believe the focus of his research was mainly on crating a sterile triploid fast growing sunfish, which eliminates the RESxPS branch of research fairly quickly. The results of his research (from what I have read) indicate that he did not view the RES x PS hybrids as viable for his purposes because they were so genetically close. For my research however, this would be a positive.

I don't think the RES & PS cross very easily under natural conditions, so in order to breed them, I will have to get a little freaky with them and a pyrex bowl (I'll be sure to dub some Marvin Gaye over the video; too far? :)).

We're a long way from that point but you have to have goals and I personally think this a worthwhile experiment. I know if there was a local hatchery that sold sunfish with the snail appetite of RES and the cold tolerance of PS, I would buy them in a heartbeat.

To be honest if it weren't for the risk of parasites, I would just fill a pond with bluegill and a couple of HSB, grow them out on Aquamax and be done with it... maybe.

Are there any members from the north, (outside of the RES comfort zone) who have filleted a yellow perch/sunfish that was filled with parasites who think this isn't worth attempting?

Most likely not. The RESxPS hybrid picture that I have seen looks just like a RES to me however, I am novice taxonomist.

Todd, that's also why you ask questions and elicit answers that a judge and jury can understand. Nothing can ever be considered intuitively obvious.

I haven't been on the nanfa site in a long time, good info I'll check that out.

DMRBG, I think your experiment is great. If you could get cold tolerance, snail appetite and resistance to stunting I'd be very interested. I've been toying with the possibility of adding single sex PS to a YP/SMB pond for snail control. Unfortunately, one mistake with the ID and the whole thing could nosedive.

Speaking of which, how fecund is the RES x PS hybrid?

I personally cannot answer that question from experience yet however; from what I have read so far, I expect that you would need to carefully manage the population.

Plain language and simple logic is the order of the day!

All I can say Todd, It was fun

Well, things are slowing down again and I'm back at the project. Here is the design for my RBC axle. I'm not trying to re-invent the wheel however; I do like adding my own touches to the things I build. This is going to be a scaled down version of the RBC in the book Small Scale Aquaculture. It is designed to fit inside of a 55 gallon barrel cut lengthwise at about 35% of the diameter. I think this axle design should make for easy/cheap maintenance. I'll be sure to provide actual pictures as I make the pieces.

What do you guys think of the axle design.

Will the RBC be floating, or will the axle go thru the ends of the drum?

I might add some foam along with the media disks to decrease the weight on the shaft however I have not decided how much weight I want to dissipate vs. how much media surface area I want to sacrifice yet. I might not decide that until closer to the end of assembly once I see how much weight will be on the shaft and how the plastic needle bearings will wear with that much weight.

As far as how the shaft is going to be secured, the inside shaft is going to slip inside of 1" PVC flanges attached to the inside of the barrel. The joints of the 2 PVC flanges will remain unglued.

I'm thinking the entire barrel RBC assembly will sit inside of a rigid wooden frame that should prevent the plastic from expanding outward and making the shaft slip off of the flange joints. I am also considering (most likely will be) adding a set-screw to the flange/inner shaft joints.

Hopefully Cecil will chime in here. I helped him set up his RCB both ways, and I felt that the self floating style was less dependant on a constant water level in the tank to minimize drag on the bearings.

Like Scott (Esshup) says I've done both -- a floating RBC and one where the axles go through the sides of a large tank with the ends capped. I'll take the floating hands down. Not only will it adjust with the water level there is no weight pushing down on the axle to speak of, and PVC inside PVC that is lubricated with water lasts indefinitely.

One of the downsides to typical nonfloating RBC's is the weight the axle has to endure. As bacteria builds up on the surfaces of the RBC it really adds up. It's a tremendous amount of weight and historically a lot of RBC axles have snapped if they didn't float. Not that it can't be done though.

Thanks for the pointers Cecil. I'll work on the design some more. I have some ideas for modifying my design to be free floating that I want to plan out some more. I'll post here when I have a more complete plan.

Here is the latest plan that I have drawn up. The dark grey is 1" sch 80 PVC, the light grey is 1.5" sch 40. The main outer shaft is 2" sch 40. The blue is foam, the green is the media, and the light grey outline is the cups.

The design is going to be free floating attached to a 1.5" T fitting that is going to have a 1.5" sch 40 piece about 1/2 in longer than the bottom of the rbc. This way if it bottoms out it will still be free floating and spinning. The 1" sch 80 shafts will connect to the outside of the barrel/barrel housing and the 1.5" sch 40 will slide up and down these 2 shafts freely. I decided to use 1" to 1.5" bushing rather than 1" couplers to keep the needle bearings in place since the outside diameter of the bushing is about perfect.

Nothing in the image is to scale; it is just something I whipped up in mspaint to visualize my idea.

Let me know what you think.

The concept looks quite reasonable.

The needle bearing idea will probably work, but not as easily as you think. In a perfect world, that being, all the materials came in at size, you will have some interference. A bit of machining will solve the problem. I would also consider spherical UHMW bearings, instead of the roller, if you think you need a bearing at all. All you really need is a retainer if it is floating.

Don't expect your schedule 80 grey pvc to be super rigid.

PVC is also a very poor bearing material (not even listed as a bearing material). In Cecil's application, the PVC is acting more in the fashion of a retainer to keep the axis of rotation, well, retained, and not as an actual bearing. Put a cylinder in water with external forces without retaining the axis of rotation and it will be uncontrollable. I personally would not worry about PVC as a retainer, but don't use it in a load carrying bearing application.

What media are you using?

Since you posted this. I was playing around with the idea of using 10MM twin wall corrugated polypropylene as media. That would work quite well. A 2ft diameter x 4ft long RBC would be in excess of 1100 sq ft, plus it is buoyant.

Look into the history of RBC's and you will find that they were Engineered for treating municipal waste water, with good success. The problem with the axles snapping and bearing/mechanical failures came about when some fish guy's, without engineering skills tried to duplicate this. They use to use plywood for media. These however, were the pioneers in Aquaculture, and a Big Thanks to them!!!

RBC's for Aquaculture have come a long way since then, and everyone has their flavor.

Nice device for doing the task at hand. And as I said earlier, you can thank the Aquaculture Pioneers for this.

Let us know how things are going.

DMRBG,

I like it! Give it a shot! The only thing I can warn about is RBC's with media end up heavier than plates due to more surface area for the biofilm to collect on. Of course more surface area is better right? However, Dr. VanGorder actually warned me that they sound great on paper but can be incredibly heavy over time.

He said they even tried rectangular plate ones for more surface area and ending up scrapping them.

I have heard of some trying square plates, and have seen some utilizing octagon shapes. Round takes less power to rotate in water because it is not trying 4 times (square) per revolution to create a new path thru the water. That takes a bit more power. If you rotationally staggered them, it would be less power, but now you are basically back to a circle, If you get what I mean, which takes even less power, and creates more surface area.

Yeah Phil I think they burned up the motors or something if I recall correctly.