Well the RAS (Recirculating Aquaculture system) I built from the directions in the book Small Scale Aquaculture by Steve VanGorder is finally up and running. I wanted to bring the rotating biodisk filter I had built to the convention this year but didn't make it for lots of reasons. Maybe it was better I didn't as I am now finally getting experience using it in the completed system. However if Bob is still interested I'd like to so an article on this as an indoor alternative to winter over fish or just keep the fish bug biting during the long winter. It's also an excellent way to raise fish for the table. I want to give special thanks to Steven Van Gorder for his excellent book Small Scale Aquaculture. He has also patiently answered my email questions free of charge even though he consults for a living.

Anyway, an epoxy coated stock tank is set up on cinder blocks and 2 by 10's. I have two of these tanks I traded for fish mounts. The tank is holding somewhat less than 324 gallons due to displacement of the biofilter disk.

There is a 2 inch diameter PVC "U-tube" siphon pulling water out of the bottom of the stock tank, which brings with it particles and other solid waste into the bottom of a separate 55 gallon drum know as a "clarifier." The particles are trapped under and inside netting that is packed into the 55 gallon drum. These waste products are periodically drained out of the bottom of the 55 gallon drum (clarifier) via a fitting and hose that comes out of the bottom of the tank, and flows via gravity into a floor drain once the hose is laid on the floor. (It's in an upright position above the water line when not in use). I'll probably get more sophisticated with an actual open/close valve later.

Water is pulled up out of drum (clarifier) via a 5 gpm pump resting on top of the netting in the drum, and is fed into a fitting in the frame of the biofilter disk. There it comes out over a series of PVC paddles, which catch the water and rotate the biodisk filter. The filter rotates on a PVC axle.

I had to raise the stock tank via cinder blocks so the top would be even with the 55 gallon drum that is used as a clarifier. (The actual tank used in the book is a 12 foot diameter swimming pool that is 3 feet deep vs. the 59 inch tank and only 20 inches of water I have in my tank.)

The frame of the rotating biofilter disk is an inch too wide to float in the tank , so I have it suspended from the ceiling of the back room in my walk-in basement via chains. The frame also partially rests on the top of the stock tank at an angle. This puts the axle of the rotating biofilter disk where I want it which is just above the water level.

It will take a few weeks to get the bacteria up to full capacity so there are no fish in the tank right now. I have about 5000 YOY 3/4 inch bluegills (weren't hatched until September) at my disposal in a floating cage. I may put a few in just to feed and get the biofilter going. Or I may add some ammonia, or fish feed, and then put the entire amount of fish I want to put in once the tank is "cycled."

I was going to use this tank this fall for some broodstock pumpkinseeds but the producer wants to wait until spring. My goal now is to get experience and see what kind of growth I can get over a year's time with constant temps.

The rotating biofilter disk rotating with an agitator running to the right (probably won't need the agitator initially for the load I am planting.) Note the white hose that feeds water from the clarifier drum into the frame of the biofilter. The water then drops over the paddles turning the biofilter.



Here's a look at the biofilter frame showing the axle. The 1 1/2 inch axle is enclosed in a 2 inch section of PVC which in turn is enclosed in a 3 inch section.



The siphon. The book simply calls for a "u tube" with an end cap and detachable piece but I opted for something a little more sophisticated and easy to make work. That is a check valve on one end and a threaded end cap on the other. On top is 't' where water is poured into to fill the u tube and capped. To start the flow a short section on the drum side, that is not glued is removed. Once the flow is started the short section is pushed back in (slip) with the threaded end cap removed. The water in the barrel clarifier will stay at the same level as the stock tank as long as the "u tube" is not blocked in any way.



The siphon in postion:



A look down into the drum clarifier showing the return pump to the biofilter and the bottom of the "u tube." Note the bulkhead fitting on the bottom of the tank which is connected to a threaded and then barbed elbow and a clamped hose for draining the barrel.



1/8th inch mess put into the bottom of the check valve to keep the small fish in the stock tank. It seemed good on paper but in reality it wasn't such a good idea. It reduced flow enough for the incoming siphon water to get behind the return flow of the pump. This lowered the tank water and started the pump running dry. I have removed the screen with no further problems. I will either put a cage around the intake where the check valve is, or build a large cylindrical shaped screen around it.

Edit: I believe the check valve may be the culprit not the screening. With the check valve removed so far the water level is staying the same in the stock tank and the drum clarifier.




An iron filter I had installed to remove the iron from my well water, which is used to replace the water that is drained from the clarifier. I have softened water I could use, but it's not as good for the fish as the hard water is minus the iron.

What a great start for a thread. I'll anxiously await updates. I'm about a year away from trying my own system, so I'll be taking notes!

Thanks for the kinds words Bruce. Keep in mind there is more than one way to skin a cat and there are other ways to get the job done. I was told by one old pro that what I'm doing is obsolete. According to another the following has 6000 square feet of surface area for one foot of media and has a smaller footprint.

http://www.bioconlabs.com/abtqs.html

And then there's AP's system which seems interesting too.

BTW I may have spoken to soon on getting the siphon right. For some reason the pump is staying ahead of the siphon. Over time the clarifier is getting lower than the stock tank until it eventually leaves the pump high and dry. It's either the check value is reducing the diameter of the gravity flow or the pipe lengths need to be adjusted.

I see you got it running. Looking good! Just throw some canaries in there and you'll be fine!

Goldfish, FHM, GSH? Who will be the canary?

Cecil, the check valve in your U-tube will require some pressure before opening and is probably the culprit. The screen you showed in the pic didn't appear too restrictive to me. Consider removing the check valve and adding a screen on both end of the tube to prevent fish entering the clarifyer.

That looks great Cecil. What temp do you plan on keeping in the system ? One suggestion for a growth trial test. Use either all males or all females or at standard room temp 70 F soon ( 6 mths) they will get territorial and start spawing every 40 days + -. Also check/manipulate the photoperiod for growth and reproduction.

Nice job, Cecil.

Actually the check valve has no problem opening at first. Perhaps it has trouble staying open when the flow stabilizes and is reduced to the flow of the pump after the tank and barrel water are the same level? I'll take the check valve off and use an end cap on both ends after filling and see if that solves the problem. The check valve no doubt is designed for water under pressure.


Thanks Rex you da man! Fish transporter, dog transporter, mechanic, and now plumber!

The canaries will be bluegills that have been treated with a salt dip or PP to remove an external parasites. I may add some treated fatheads to get the bluegills feeding if necessary as they really like the fish feed in the pond! I can put fish food in a minnow trap and pull up about 10 dozen in a half an hour. With no bass in the pond other than SMB fingerlings the fatheads number in the 10's of thousands!

I'm waiting to find out from Steve VanGorder what a safe amount of fish weight to add would be to get the bacteria started effectively but not lose the fish.

Even though Steve runs an RAS consulting business he has been vary patient answering my emails at no charge. I sent him two more questions (siphon tube problem and how many fish to add initially), and promised him there would be no more questions!

If I don't heat it will stay at 68 F perhaps a little cooler this winter. I know I could get faster growth and better bacterial performance if I do heat though.

The bluegills are only 3/4 inches maybe 1 inch in size at this point. I'm hoping I can keep territorial behavior down once they get bigger by the density of the fish. At peak performance the RBC is supposed to be able to handle over 100 pounds of fish. Of course I will stay somewhat conservative though.

I may just move some all out to cages next year once they reach a certain size.

Cecil,

What is the purpose of the "rotating" biofilter disk. Is it using the paddle wheel effect to aerate?

Can you take a photo of the the entire overall system.

This looks great!

Cecil, that's a neat system, if the fish get bored they can take a ride on the biofilter drum.
Are you planning any special diet for them?

Jeff,

The plates of which there are 50 cut out of fiberglass roofing and 50 out of .20 thickness polystyrene plastic are 600 square feet of surface area for the bacteria species that will grow on them, and change ammonia waste products to nitrites and then harmless nitrates. There are two species known as nitrobacter and nitrosomonas. They need aerobic conditions and of course water to thrive, so the rotating biofilter disk provides aerobic conditions by exposing them briefly to air and then submerging them again. The paddles cause the biofilter to rotate on it's axle by filling with water. They also provide some aeration.



Yes. I think I may also draw a diagram with flow direction etc., which may make it clear how it works. It's not really rocket science because if it was I would be more lost than I am.

Hey did you know this same Rotating biofilter disk was used in Biosphere II? Here are three joined together in a greenhouse from the book Small Scale Aquaculture by Steve VanGorder:



The book is awesome and covers everything from flow through systems to aquaponics and on and on. One should be able to find it for under $30.00.

They're going to be raised as fat liberal moochers so most likely they will try and get a free ride. (Being this is a liberal household).

No special diet. I still have all sizes of Aquamax I can use to feed them.

I've been feeding the PS's very heavily and they always seem hungry.
The ammonia has not gotten much above 1.2, but with a ph around 6 ammonia is no problem.
The nitrites are reading 0 so the filtration seems to be doing the job, I also vacuum the tank twice a week replacing about 20 gallons of water, and flush the bead filter once a week.
They are fed mostly salmon with some krill and Tetramin granules.

How long have they been in there and have you observed any growth? These were wild fish right?

Cecil,

It looks like you have done an excellent job! I am looking forward to hearing how the water quality goes and of course, the fishy things that you will do with that setup.

One thing I am curious about is why you didn't go with a rechargeable iron filter?

Cecil, it's been almost 6 weeks since the PS's were brought in from the backyard pond and they ranged from 7 to 9 1/2".
If I was scientific about it I would have tagged and weighed them but that's not me.
They certainly are fat and active but I'm gonna wait a couple months before taking some measurements, so their not stressed too much.
Some came out of my pond but the biggest ones came from my favorite little mountain lake that is loaded with PS's.

Well you're probably more familiar with these kind of things but I think it is rechargable? That is the water softener company comes out every three months and replaces it with another one. They told me they have another company that recharges them or does something to them. Some kind of resin that attracts the iron?

It's what they offered (Culligan) and seemed pretty reasonable for 44 bucks ever three months. It doesn't use any power but runs via water pressure.

Perhaps you're talking about a brim filter?

I do know it doesn't take out 100 percent of the iron. I get a temporary green coloration a few hours after running water into my make up water tank, which tells me there is a weak solution of suspended iron. When I get more reagents for my iron meter I'm curious to see what's left. What little there is however settles out in few days and the fish tank water is gin clear.

I can concur about not stressing fish. Whenever I move fish or plant fish I'm tempted to take a lot of measurements but usually don't. I've seen problems when you handle them too much.

I did take a lot of measurements once before and after for an article. Guess what? I can't find the damn things! Shows you how scientific I am!

I added two teaspoons of household ammonia today. Now the waiting games begins until the nitrites appear, spike, and dissipate.

I would have preferred to add a few fish and feed them, but VanGorder says that takes longer and is riskier for the fish.

I sure hope the cage isn't frozen in by the time I'm ready to move the fish.

Siphon is working great without the check valve. That's what happens when you think you can reinvent the wheel.

Do you plan on vacuuming the tank occasionally or do you think the clarifier and biofilter will keep the stock tank clean?

If the water is kept moving by the RBC and the agitator it should keep the crud moving and suspended to be sucked up by the siphon and then trapped in the clarifier. At least that's the plan. According to the text, "these devices are capable of removing nearly 100 percent of the settleble material suspended in the water column, with very low energy requirements."

Update:

No more problems with the siphon. As per advice from Steven VanGorder the author of Small Scale Aquaculture I must have had a small leak allowing air in which slowly built up an air bubble and stopped the siphon. I can back that up as the last one I built that failed, had tiny air bubbles coming out of the intake into the clarifier.

So I rebuilt one making sure to hold the pieces in when glued, and without a 't' which may have been letting air in via the "cleanout." No problems in four days and no change in the water level in the barrel clarifier.

Now I'm waiting for the nitrites to appear to indicate the nitrosomonas bacteria are starting to work. Two weeks and the only thing I'm reading is the ammonia I've been adding to feed the bacteria. I've read it may take up to 8 weeks to get the bilfilter cycling although 4 to 6 is more typical.

I did seed the tank with some alleged bacteria in a bottle from an aquarium supply store, but according to some guys on the NANFA site it's not effective unless it's a particular brand of which mine was not.

I'm going to have to chop ice to get the bluegill fry out of the floating cate to plant the tank. With my luck I will have all kinds of fungal problems from handling them in the cold water even though I will acclimate them (fry bluegills). The story of my life: A day late a dollar short.

Sounds like you've got it down well Cecil.

Cecil,If it was easy everyone would be doing it, although most of the time it seems to end up being harder than we expected.
I'll bet your BG will be real happy to get out of the arctic cages.

Cecil:

Give me a shout if you need a hand. It sure got cold and icy quick!!

Probably the most important thing to do in a RAS is to remove solids as quickly as possible. A swirling solids settling tank would be worth looking at. You would place it in front of your clarifier. A well setup settling tank let's you "flush" the solids out of the bottom as needed, much like flushing a toilet. It really cuts down on the time spent cleaning filter media, and it really helps to keep the whole system running smoothly.

Weissguy is correct. It is the solids (suspended and dissolved) that are most responsible for causing reduced water quality in RAS and natural ponds. The more crowded a system becomes the more important it becomes to process the solids.

Thanks for all the info guys. I definitely know how solids and dissolved solids etc. can dirty up the water and reduce water quality. I've seen it when I was temporarily holding some bluegills in this tank outdoors, when I had to drain the production pond and start over. I ran flow through from one of the ponds through the tank but the water still got pretty dirty.

And a venturi drain will be the choice de jour next time I set this tank up.

I hope to soon put the RBC in a separate rectangular tank
at a level above the fish tank, to allow overflow to return flow into the tank via gravity so another pump does not need to be added. Lots of advantages to that, including isolating the RBC to treat the fish in the tank if necessary, and simply having more room in the fish tank itself to harvest fish etc. With the smaller than optimum size of the tank I'm using now, flow in the tank is not circular like I would prefer.


The big plan it to get experience with what I have, and then try different types of setups and combinations and build everything myself. I'm pretty sure I could build a foam fractionator and swirl separator, which look pretty effective. In fact, a lot of the things they use in RAS technology look like they can be built yourself -- at least on a small scale. I see they make foam fractionators for aquariums. I looked at one at Pet Store the other day, and it didn't look that complicated. Basically air foaming the water and the foam with the particulates and protein flows away.

I'm going to try and use gravity as much as possible to move water to keep utility costs down. And most likely I won't be interested in pushing the limits on carrying capacity. My goal is fast growing high quality disease free fish.