Pond Boss Magazine
https://www.pondboss.com/images/userfiles/image/20130301193901_6_150by50orangewhyshouldsubscribejpeg.jpg
Advertisment
Newest Members
Jhawk, BattleRidge, RemingtonRanch, JSkid2, IND1371
18,416 Registered Users
Forum Statistics
Forums36
Topics40,839
Posts556,269
Members18,417
Most Online3,612
Jan 10th, 2023
Top Posters
esshup 28,289
ewest 21,454
Cecil Baird1 20,043
Bill Cody 15,075
Who's Online Now
0 members (), 263 guests, and 182 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Joined: Aug 2002
Posts: 20,043
Likes: 1
Hall of Fame
Lunker
OP Offline
Hall of Fame
Lunker
Joined: Aug 2002
Posts: 20,043
Likes: 1
One of the advantages of a circular tank is it's self cleaning ability. And that is the major reason I use them. In square or rectangular tanks solids can collect in corners and be difficult to remove. Usually not is issue with tilapia, as one can purposely keep it in suspension to remove, but other species aren't as tolerant. Or you can spend time removing the solids manually.

A circular flow can be set up to cause settleable solids (feces and uneaten feed) to move toward a drain in the center of the tank. (Known as centripetal flow or the tea cup effect). This is done by creating an inflow that is tangential to the inside wall of the tank. Koi pond folks call them TPR's. (Tangential Pond Return.) More in another thread.

Or one can alternately mount a diffuser directly above the drain which pushes up water, and pulls it back down the outside edges of the tank and then to the center drain. Or one can do both. I prefer to do both. Obviously the diffuser has a dual effect of adding oxygen to the water.

Here is an illustration of how that works, although my airline comes into the top of the tank and my return flow is a DIY mounted spray bar with a vertical and horizontal axis. (To be covered later).



In this thread I'll concentrate on the center drain, but it was important to explain the above to show what role the center drain has in a circular tank, how you can build it yourself, and how it works to collect solids or at least pull them out periodically when a knife gate valve is opened.

Solids in a tank consist of settlable solids AND suspended solids. Both consist of waste products produced by the fish an uneaten feed. A good system will remove these as soon as possible, as they not only are a conduit for bacteria, but can irritate the gills of fish. The center drain is my vehicle to remove settleable solids. To be covered later I use a PVC siphon to remove the suspended solids and settleable solids that have not settled via gravity.

I make my center drains out of a 3 inch PVC shower drain or a vent cap. I prefer the vent cap when I have very small fish as they may be sucked out with the shower drain. Both can be purchased at hardware stores or big box store like Menards or Home Depot and will be glued inside a 3 inch PVC pipe.

Two different size vent caps that can be used as a drain.



A shower drain:


I first glue a PVC end cap on a section of 3 inch PVC with PVC glue, and let the glue cure overnight.



Then come back with a chop saw and cut most of the cap off to leave a retainer ring on the outside of the 3 inch pipe.

Here is the result:


Here's a 3 inch shower drain glued into the PVC pipe also showing the retainer ring.



Inside view of shower drain glued to PVC pipe section:



Since I prefer to use a Uniseal vs. a bulkhead fitting to install the drain and pipe, this glued on retainer ring keeps the shower drain or vent cap from slipping through the Uniseal. The original lip on both drains isn't quite wide enough to prevent that.

If you're not familiar with a Uniseal they are a type of fitting that looks like this.



They are made of a MPR, rated to 40 psi, and warranted for 25 years. They are immune to cold, will not harden, and hold pressure and vacuum. They fit PVC pipes from 1/2 inch to 6 inches. You can use them on curved surfaces like plastic drums and other PVC pipe. However I do prefer a bulkhead fitting is if I want to place a fitting in the bottom of a drum and it has a high seam line there. A downside to unseals are they are limited to material 1/2 inch thick or less. Most plastic tanks are 1/2 inch or less though. And you must make a precise hole with a hole saw.

I also prefer a Uniseal because it's much cheaper than bulkhead fitting of the same size, and it doesn't create the profile a bulkhead fitting makes, in the the bottom inside of the tank, where settleable solids can get trapped up against it.

Here is what they look like when installed in a tank wall:



When the pipe is shoved through the fitting expands to make a water tight seal.

An appropriate size hole is cut for a 3 inch Uniseal (4 inch hole saw). Unlike a bulkhead fitting the hold has to be precise with no irregularities.


Next I grind down the edge of the other end of the pipe to fit through the Uniseal to a make it possible for the pipe to fit through. I also rub vaseline on the pipe. Otherwise if is very difficult to slide the pipe through. It's a very tight fit which does NOT leak.

I insert the Unseal with the wide side up and then push the pipe in as much as I can with my hand. Standing on the drain if the tank is elevated should push it in all the way to the retainer ring you created.


Last edited by Cecil Baird1; 02/09/16 09:35 AM.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.






Joined: Apr 2002
Posts: 15,075
Likes: 455
B
Moderator
Ambassador
Field Correspondent
Lunker
Offline
Moderator
Ambassador
Field Correspondent
Lunker
B
Joined: Apr 2002
Posts: 15,075
Likes: 455
Informative and a relatively simple system for removing solids in a RAS. Thanks for sharing the info.


aka Pond Doctor & Dr. Perca Read Pond Boss Magazine -
America's Journal of Pond Management
Joined: Aug 2002
Posts: 20,043
Likes: 1
Hall of Fame
Lunker
OP Offline
Hall of Fame
Lunker
Joined: Aug 2002
Posts: 20,043
Likes: 1
Once the drain is installed it's a simple matter of connecting a rubber Fernco coupler to the connect another section of pipe to the floor followed by a three in inch elbow. Then a section of 3 inch pipe (all 3 inch pipe) runs along the floor to a knife gate valve to which is also connected on each end with a Fernco coupler.

Next comes a t and a vertical stand pipe with a vinyl hose that is directed to a drain or waste line.

Twice a day I pull the knife gate handle and this flushes waste laden water from the center drain and around the center drain. I vinyl hose on the other side of the vertical stand pipe turns dark momentarily with waste.



Shower drain installed in the bottom of a plastic tank. (Previously used a washer shaped piece of heavy plastic as a retainer ring.



Picture showing sequence of shower drain glued to PVC pipe, Uniseal, and Fernco coupler. Tank not shown.


The drain, PVC pipe couplers, knife gate valve, fittings, and standpipe minus the tank.


Contrary to what you may think the stand pipe needs to be higher than the water level of the tank if you use it to purge waste products. The forceful surge up the standpipe to briefly remove solids causes it to rise higher than the water level. Learned this the hard way after I got wet the first time!

Obviously the the stand pipe has to be in a vertical position.

I prefer the fernco couplers vs. gluing fitting together as it allows me to take things apart easily for relocation and cleaning when I temporarily shut down a system.

Here's a close up of where reducers and a barbed fitting were attached to install the vinyl hose as a waste line.



Note: A knife valve developed a chronic leak at one the high schools I installed a system at. I added an additional ball valve downstream of the knife gate valve inline of the vinyl hose to preclude losing water from the system. This was cheaper than purchasing another knife valve, and the problem of disconnecting even temporarily a system full of fish and water to install a new one! Can you imagine the water rushing out of a 3 inch pipe while frantically trying to slide on a fernco cooler and tightening it?!

Last edited by Cecil Baird1; 02/09/16 09:32 AM.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.






Joined: Dec 2009
Posts: 6,692
J
JKB Offline
Hall of Fame 2015
Lunker
Offline
Hall of Fame 2015
Lunker
J
Joined: Dec 2009
Posts: 6,692
Cecil, got a figure on how many miles/hours particulate matter that we would want out of a tank as soon as possible will hang around in the tank, while on the trip will it be breaking down into dissolved solids on the journey?

Saw some Physics stuff a few years ago where they were marking stuff with dye and tossing it on a puter to see what actually happens in a round tank with fish poo and solids in it. It was the centipede wink flow you keep mentioning.

My liking it so keep it to a DIY rig, as it is and don't toss in things you may not fully understand.

Cool tho! cool

Carry on...


Last edited by JKB; 02/08/16 09:38 PM.
Joined: Aug 2002
Posts: 20,043
Likes: 1
Hall of Fame
Lunker
OP Offline
Hall of Fame
Lunker
Joined: Aug 2002
Posts: 20,043
Likes: 1
Originally Posted By: JKB
Cecil, got a figure on how many miles/hours particulate matter that we would want out of a tank as soon as possible will hang around in the tank, while on the trip will it be breaking down into dissolved solids on the journey?

Saw some Physics stuff a few years ago where they were marking stuff with dye and tossing it on a puter to see what actually happens in a round tank with fish poo and solids in it. It was the centipede wink flow you keep mentioning.



Oh sure there will always be particulates breaking down into small particulates. The trick is to keep it as minimal as possible. As you know the worst thing you can do is use a pump inside a fish tank which might as well be a high speed chopper! That's why I like my siphons as they gently remove suspended solids 24/7 via gravity and trap them in the clarifier.

The ultimate would be to run the bottom drain and a side filter (Cornell dual drain or Eco trap) continuously to a filter that takes the solids out immediately like a rotating drum filter or a sieve wedgewire filter. Unfortunately for my small scale systems they are out of my price range and would be overkill for my smaller fish loads.

I believe I saw some research on the Cornell Duel drain that showed a residence time of 10 minutes for solids? They used some beads with the same specific gravity to do the research.

I watched a pinched pellet that was laying on the bottom slowly makes it's way to the center drain.

Last edited by Cecil Baird1; 02/08/16 09:42 PM.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.






Joined: Dec 2009
Posts: 6,692
J
JKB Offline
Hall of Fame 2015
Lunker
Offline
Hall of Fame 2015
Lunker
J
Joined: Dec 2009
Posts: 6,692
None the less, should be a good documented primer on how to poke some fish in water for their individual purpose. Also kinda fun!


Last edited by JKB; 02/09/16 08:52 AM.
Joined: Aug 2002
Posts: 20,043
Likes: 1
Hall of Fame
Lunker
OP Offline
Hall of Fame
Lunker
Joined: Aug 2002
Posts: 20,043
Likes: 1
Here is an example of installing a drain by trenching it in. This is a koi pond where either a liner goes above it (drain is two part and clams onto liner) and or concrete is poured over the drain pipe etc.



Most koi ponds are basically low density RAS's.

There are several types of drains sold for koi ponds that could be used in an Intex pool.






You can also build your own. Note the molded in air line attachment. This keeps keeps the airline out of sight for aesthetic reasons in a koi pond.

Btw the way the dome serves a purpose. Without it there can be a vortex above the drain which can impede the self cleaning. They are appropriately called anti-vortex domes.

Last edited by Cecil Baird1; 02/09/16 09:59 AM.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.






Joined: Jan 2006
Posts: 2,386
B
Ambassador
Field Correspondent
Lunker
Offline
Ambassador
Field Correspondent
Lunker
B
Joined: Jan 2006
Posts: 2,386
Cecil, you are very kind to put so much time into showing how you created your RAS. I also like you so I'm a bit hesitant to crack on ya but just have to. I remember you and Cody had an interesting discussion about the shape of cages. You stated that Bills cages very much resembled your wife's wastebasket and even posted a pic of it. Now here you are promoting round tanks. Go figure.

Cody Note. I also found this an interesting turn of opinion. There are advantages to round / cylindrical tanks and cages. CB1 knew that and was just "crackin" on me at the time.

Last edited by Bill Cody; 02/09/16 03:27 PM.

Do nature a favor, spay/neuter your pets and any weird friends or relatives.

Link Copied to Clipboard
Today's Birthdays
Reno403
Recent Posts
Otters Strike Again!
by Rangersedge - 03/01/24 10:03 PM
HOA pond got drained and nobody knows why
by Rangersedge - 03/01/24 10:00 PM
Red mouth
by shooterlurespond - 03/01/24 09:43 PM
Chestnut other trees for wildlife
by Rangersedge - 03/01/24 09:32 PM
Osprey Goes Double Fisted
by FishinRod - 03/01/24 09:11 PM
New pond middle TN: establishing food chain?
by Bill Cody - 03/01/24 08:09 PM
What Kind of Moss?
by Bill Cody - 03/01/24 07:48 PM
HBG - Catfish
by FireIsHot - 03/01/24 05:18 PM
Managing black crappie
by Pat Williamson - 03/01/24 02:49 PM
Fountain Location?
by TigerFanatic1 - 03/01/24 12:28 PM
Help with everything
by FishinRod - 03/01/24 11:03 AM
Low pH, low Alkalinity in Fresh ponds/Lakes
by ewest - 02/29/24 01:29 PM
Newly Uploaded Images
Eagles Over The Pond Yesterday
Eagles Over The Pond Yesterday
by Tbar, December 10
Deer at Theo's 2023
Deer at Theo's 2023
by Theo Gallus, November 13
Minnow identification
Minnow identification
by Mike Troyer, October 6
Sharing the Food
Sharing the Food
by FishinRod, September 9
Nice BGxRES
Nice BGxRES
by Theo Gallus, July 28
Snake Identification
Snake Identification
by Rangersedge, July 12

� 2014 POND BOSS INC. all rights reserved USA and Worldwide

Powered by UBB.threads™ PHP Forum Software 7.7.5