Help me build a closed system

[Ronster]

I want to build a small closed system at my house.   Figuring on 20-30 crabs at any given time.   Looking for advise or tips on setting it up and setting up a basic filtration system.   Not trying to get too fancy or expensive.

First question is, can I use these as the holding tanks.    Why or why not?

http://www.grainger.com/Grainger/RUBBERMAID-Stock-Tank-1MDC1?Pid=search

[rdbeard]

That's what jack uses now, he should be able to give some info although he's doing an open system. my first set up was a 30 gallon aquirium and it worked good for up to maybe 20 crabs and all i used was a regular aq. pump- filter and a few more air stones.

[ChrisS]

Not sure why you couldnt. I use 2 of them for a filter.

[ChrisS]

If you know any restaurant or bar owners, they usually have a few of them laying around they use them to ice down beer and sometimes you can get them much cheaper or free, as in my case.

[Ronster]

Not sure why you couldnt. I use 2 of them for a filter.

Run through your filter process.

[ChrisS]

Well, my filter process was never quite profected, had I not changed out water based regularly, I got alot of stills. So, I might not be the best one to ask about that.

[Mr. Ray III]

Ron you don't need to buy those tanks.  Use 2x10's and plywood.  Silicone it to stop it from leaking or let it swell.  

Why?  To save you money.  If your only gonna be holding 20-30 crabs, you only need a very small set up.  You do not need more than one tank and a 4x8 tank will be way more than you need (keep in mind, NC boys will put 400-500 in a 4x8 tank).  Make it a 4x4, put a divider in the midde for your ranks and greens.  

[KI Crabber]

I use  the 150 gallon version with about 50 gallons of water. I can keep 20-30 crabs for about 3 weeks before water quality is an issue. I don't filter at all, just have a layer of gravel in the bottom of my tank and swap water out every few weeks. I carry a 12 volt inverter with an extension cord, 120 volt submesible pump and hose. I fill my containers at the ramp with seawater and pump it from the truck to the tank at the house. I shed about 16 dozen last year in my basement and only had about two dozen that didn't make it.

[jack1747]

If you use the stock tank/s you can build a table for it then use a dry sump filter for saltwater aquariums. It would work great. No worries about leak either. Easy to clean. I got a pump for ya...

[Ronster]

Ron you don't need to buy those tanks.  Use 2x10's and plywood.  Silicone it to stop it from leaking or let it swell.  

Why?  To save you money.  If your only gonna be holding 20-30 crabs, you only need a very small set up.  You do not need more than one tank and a 4x8 tank will be way more than you need (keep in mind, NC boys will put 400-500 in a 4x8 tank).  Make it a 4x4, put a divider in the midde for your ranks and greens.  

Yeah.   I tried putting the 4 x 8 plywood set up past my wife and it got vetoed because "you have enough frankensteined looking stuff in the yard."   She's good with the stock bins.

[ChrisS]

I would think plywood alone, would leak. I lined my wih pond liner.

[crab24]

I would think plywood alone, would leak. I lined my wih pond liner.

it will leek no matter what but if you use gluvit it will work .

[Ronster]

The plywood is out because of the look of it.    The wife want's the tubs back there instead.

[KI Crabber]

If they are outside make sure you have them covered so you don't collect too much fresh water during rain storms.

[Mr. Ray III]

I know your gonna need a buncha oyster shells   

[bigcrabrob]

plywood dont leak if done right . i have 6 shed tanks 4x8 made from playwood and i got 5200 on all the joints so it doesnt leak . after you use the chalk run the system and drain it to get all the chemicals out

[Ronster]

I know your gonna need a buncha oyster shells   

Something an up and coming oyster farmer has in abundance.

[ChrisS]

Ronster, I would suggest looking at "Bio-balls".

[jack1747]

Go with a dry sump. My Son runs 3 500 gallon reef tanks. If a dry sump filter can keep them going, a float with a few peelers is piece of cake...

[Ronster]

I just acquired my pump.

[Ronster]

How about filter design?    Can anyone help with that?

[scoopnet]

Try going to"Technical Resources". Scroll to the 3rd PDF file "Design of recirculating blue crab shedding sysems"> go to page 60. I used 3 rubbermaid 32 gal. "Brute" garbage cans with rubber gasket bulkhead fittings and 1-1/2" PVC pipe. It works great.  I used clam shells and dolomite gravel in the filters. You can get by with just one filter and the sump for a small tank. If you are using oyster shells, you may want to break them up a little to give more surface area for the bacteria to grow.  Put a removable screen or fiberglass filter at the end of your shedding tank return line to collect the solid waste before it gets into the filter material.  There is also a lot of info. on water chemistry at that site. I used Gluvit on my shedding tank. It works great with 2 coats,but is expensive. Buy it on line at Neals Harbor.com no tax/free shipping best price I could find.

[bigcrabrob]

i put a screen on top on my return tank so it collects all the big stuff . i use oyster shells for filter in one tank and it goes into another tank where the pump is . works great and cheap just go to a oyster house and ask them to same you the shells .

[MDblue1984]

If you use the stock tank/s you can build a table for it then use a dry sump filter for saltwater aquariums. It would work great. No worries about leak either. Easy to clean. I got a pump for ya...

I would be worried keeping them out in the sun like that.. As hot as the summers get, with black plastic, would you prematurely cook your catch?

[Ronster]

The spot where I plan to put this doesn't get a lot of direct sun.   It's between the north side of my house and a fence, in a narrow area, so there is little opportunity for direct sunlight there.