Chop 1 or Chop Mark 2 System???

[Gene Carr]

What is the benefit in CHOP MARK 2 system of having the water split to flow to the fish tank and grow bed at the same time? Why is that preferable over the CHOP 1 SYSTEM?

[TCLynx]

Oh, this discussion probably deserves some diagrams

Anyway, lets start with what does CHOP mean?

Constant Height One Pump  Basically a system where the water level in the fish tank doesn't fluctuate because the water flows out an overflow into the grow beds then drains into a sump tank where the pump is and the water level in the sump tank fluctuates.

Pretty much the same thing as a CHIFT PIST system just using fewer letters.  Constant Height In Fish Tank Pump In Sump Tank.

CHOP Mark 2 is just a modification that allows more flexibility by letting the fish tank drain into the sump tank and the pump pumps out to the fish tank as well as the grow beds and whatever else you might be using.  This allows for easier arranging of heights since you don't have to have the fish tank over flow above the grow beds and you don't have to have the grow beds blow the fish tank overflow.  There is also the option to add a pump so one could run a pump constantly to aerate the fish tank and a separate pump to do timed flood and drain of the grow beds but then it wouldn't be CHOP anymore but CHTP but anyway, this would be the easiest method to manage a Constant height in fish tank system while also using an indexing valve.

Now some people worry that the chop 2 system is sending solids down into the sump tank for the pump to then recirculate back to the fish tank.  Well if you were planning to feed NFT or raft beds from your sump tank, I would agree that this is a problem since you want well filtered water for those application but you could add supplemental filtration before those using a chop 2 system if you wished.  Other wise, the solids going into the sump have not seemed to be an issue in the systems Murray has been running.

 

So Look at your situation, space, and requirements/goals for a system to help you decide what type of system design best meets your needs.

[Sylvia Bernstein]

Hi Gene.  In Murray's blog post about these systems he goes into the advantages of the CHOP 2 over CHOP 1 - http://aquaponics.net.au/blog/aquaponics-chop-mark-2-operating-system/.  Seems to me it is mostly about having more control with separate pumps to the grow bed and fish tank.  An elegant solution, but CHOP 1 still works great as well.

[Mary Hundley]

I have read several negatives concerning the CHOP 2 system design (not on this site by-the-way) and the problem of large solid waste continually pumping through the system, breaking down, and absorbing large amounts of oxygen along the way as it decomposes.  What if a floating filter system was placed on top of the sump for the water to drain through to clean out the larger particles and changed and cleaned as needed?  The idea of the constant height of the water level in the fish tank is very appealing and the CHOP 2 system seems to address it better than most.

Sylvia Bernstein said:

Hi Gene.  In Murray's blog post about these systems he goes into the advantages of the CHOP 2 over CHOP 1 - http://aquaponics.net.au/blog/aquaponics-chop-mark-2-operating-system/.  Seems to me it is mostly about having more control with separate pumps to the grow bed and fish tank.  An elegant solution, but CHOP 1 still works great as well.

[TCLynx]

I expect that problems of solids in a CHOP 2 system are less a problem with the system design and more a problem with overstocking or over feeding.  That said, some filter material under where the water enters the sump from the fish tank might be very effective provided it is not allowed to get clogged and cause overflows out of the sump.

 

I rather like the CHOP 2 design for certain things, however My big system runs with a clean water sump (all fish tank water gets filtered through gravel beds before getting to the sump tank) because I pump to NFT pipes from that sump tank and I wouldn't want any solids going to my NFT.

 

I'm right now setting up something of a CHOP 2 design for another purpose but that won't have NFT pipes so I don't mind the solids going through the sump.

[Mary Hundley]

Thanks for the feedback...my 30x100 greenhouse is almost finished, and I am planning on an initial 2100 gallon fish tank with 350 to 500 tilapia...which should support 4 - 60 foot growbeds, each approximately 2 feet wide and 12 inches deep.  If all goes well I will added another 2 - 2100 gallon tanks and  ano another 8 growbeds....The greenhouse is 13' tall at center, so am toying with the idea of vertical stacks for basil...and perhaps an experimental NFT at the end of the run, when the water will be super clarified at that point.  Would appreciate your insights.  Thanks again, Mary

TCLynx said:

I expect that problems of solids in a CHOP 2 system are less a problem with the system design and more a problem with overstocking or over feeding.  That said, some filter material under where the water enters the sump from the fish tank might be very effective provided it is not allowed to get clogged and cause overflows out of the sump.

 

I rather like the CHOP 2 design for certain things, however My big system runs with a clean water sump (all fish tank water gets filtered through gravel beds before getting to the sump tank) because I pump to NFT pipes from that sump tank and I wouldn't want any solids going to my NFT.

 

I'm right now setting up something of a CHOP 2 design for another purpose but that won't have NFT pipes so I don't mind the solids going through the sump.

[Scott Eidson]

Mary,

If you don't mind my asking, how will you heat your greenhouse in Tenn.? I am considering somewhat the same set-up for north west GA. I have about 10,000 sqft and have not decided on the proper choice. I to am in thje process of building a CHOP 2, with a couple of changes due to having some troughs already on hand that measure 42" x 10'6" x 12" deep. These will be lined with a  pond liner and filled with pea-gravel, washed river rock. Thanks in advance for any and all input.

Scott

Mary Hundley said:

Thanks for the feedback...my 30x100 greenhouse is almost finished, and I am planning on an initial 2100 gallon fish tank with 350 to 500 tilapia...which should support 4 - 60 foot growbeds, each approximately 2 feet wide and 12 inches deep.  If all goes well I will added another 2 - 2100 gallon tanks and  ano another 8 growbeds....The greenhouse is 13' tall at center, so am toying with the idea of vertical stacks for basil...and perhaps an experimental NFT at the end of the run, when the water will be super clarified at that point.  Would appreciate your insights.  Thanks again, Mary

TCLynx said:

I expect that problems of solids in a CHOP 2 system are less a problem with the system design and more a problem with overstocking or over feeding.  That said, some filter material under where the water enters the sump from the fish tank might be very effective provided it is not allowed to get clogged and cause overflows out of the sump.

 

I rather like the CHOP 2 design for certain things, however My big system runs with a clean water sump (all fish tank water gets filtered through gravel beds before getting to the sump tank) because I pump to NFT pipes from that sump tank and I wouldn't want any solids going to my NFT.

 

I'm right now setting up something of a CHOP 2 design for another purpose but that won't have NFT pipes so I don't mind the solids going through the sump.

[Mary Hundley]

Scott,

The greenhouse came equiped with 2 natural gas heater, which I plan to convert to propane. I live in coastal Northeastern North Carolina near the Albemarle Sound, so our weather is somewhat milder in the winter than inland. My hope is the water heaters in the fish tanks (which I am insulating) will keep the greenhouse warm enough in the winter without much auxillary heat. I'll have to wait until this winter to see if that theory works...smile... I also plan on putting a second layer of film with blowers for added winter insulation. My plan is to use gravel filled troughs (24" diameter water pipe cut in half) for the grow beds, some vertical planters and perhaps an NFT raft system. This first greenhouse is a bit of an experiment to see what works best. I look forward to continued discussions, as this is a great adventure for all of us.

[Richard Wyman]

Hi TCLynx,   I have been running a system similar to Chop 2 for a year now.   The difference is I don't pump directly back to the fish, though it would be very easy to do.  I needed a system that took up the smallest footprint possible but wanted constant height. My fish tank flows to a sump, which pumps up to the beds. The indoor system has four small beds, two drain back to sump, two drain to the fish tank. The outdoor system is similar but both drain to the fish tank.   Solids build up in the sump.  It is a design thing.  The pump just doesn't lift them all. Solids pile in the center. It is a simple job to scoop the largest part out every day when feeding.  I don't overstock the system but my neighbor Franklin has a system I built him the same way. It is overstocked slightly and his cleaning is a little more work.

 Gene, The Chop 2 is a nice way to give more flexibility to your system.  This could be  an advantage for a new system owner.  You will be able to add or subtract from your system easily without shutting it down.  The only disadvantage is the slightly more time cleaning your system.   This could be easily remedied by placing a swirl filter between tank and  sump.

Good luck, and good gardening!!

  TCLynx said:

I expect that problems of solids in a CHOP 2 system are less a problem with the system design and more a problem with overstocking or over feeding.  That said, some filter material under where the water enters the sump from the fish tank might be very effective provided it is not allowed to get clogged and cause overflows out of the sump.

 

I rather like the CHOP 2 design for certain things, however My big system runs with a clean water sump (all fish tank water gets filtered through gravel beds before getting to the sump tank) because I pump to NFT pipes from that sump tank and I wouldn't want any solids going to my NFT.

 

I'm right now setting up something of a CHOP 2 design for another purpose but that won't have NFT pipes so I don't mind the solids going through the sump.

[Mary Hundley]

Richard,

Your design modification is one that I was planning to do prior to learning about the CHOP 2 system.  What is the size ratio between your fish tank and the sump that it initially flows into?  Thanks, Mary
Richard Wyman said:

Hi TCLynx,   I have been running a system similar to Chop 2 for a year now.   The difference is I don't pump directly back to the fish, though it would be very easy to do.  I needed a system that took up the smallest footprint possible but wanted constant height. My fish tank flows to a sump, which pumps up to the beds. The indoor system has four small beds, two drain back to sump, two drain to the fish tank. The outdoor system is similar but both drain to the fish tank.   Solids build up in the sump.  It is a design thing.  The pump just doesn't lift them all. Solids pile in the center. It is a simple job to scoop the largest part out every day when feeding.  I don't overstock the system but my neighbor Franklin has a system I built him the same way. It is overstocked slightly and his cleaning is a little more work.

 Gene, The Chop 2 is a nice way to give more flexibility to your system.  This could be  an advantage for a new system owner.  You will be able to add or subtract from your system easily without shutting it down.  The only disadvantage is the slightly more time cleaning your system.   This could be easily remedied by placing a swirl filter between tank and  sump.

Good luck, and good gardening!!

  TCLynx said:

I expect that problems of solids in a CHOP 2 system are less a problem with the system design and more a problem with overstocking or over feeding.  That said, some filter material under where the water enters the sump from the fish tank might be very effective provided it is not allowed to get clogged and cause overflows out of the sump.

 

I rather like the CHOP 2 design for certain things, however My big system runs with a clean water sump (all fish tank water gets filtered through gravel beds before getting to the sump tank) because I pump to NFT pipes from that sump tank and I wouldn't want any solids going to my NFT.

 

I'm right now setting up something of a CHOP 2 design for another purpose but that won't have NFT pipes so I don't mind the solids going through the sump.

[Richard Wyman]

Hi Mary,

 I have built three systems this way, the first, with two aquariums, a 29 and a 20. 40 gallons of growbed. My Twin IBC system is two IBC's cut at the 175 gallon mark. Sump and Fish tank are the same size, this will allow a 2 to 1 growbed to Fishtank ratio. The third system I built for a friend is a 150 gallon fish tank, 70 gallon sump and two 50 gallon rubbermade growbeds. The reason for the much smaller sump is that Franklin didn't have room for more beds. We maxed the space he has and he runs his system with minimum growbed filtration. He has had 30 tilapia in there for nine months without problems. ( This is twice what I recommended but they are still doing well ).

  The main consideration in sump size is how much growbed you need. A  big sump is better in my opinion. It will allow the most variability if you later want to add to the system.

[Mary Hundley]

Thanks...I have a 2100 gallon fish tank and had planned for an equal size sump, which I will eventually convert to a fish tank and add a new sump.  Initially I will have 4- 60 foot beds and ~ 350 fish.  If that goes well, will add an additional 4 beds and another 350 fish...etc....  Thanks so much for the info.  (-: Mary
Richard Wyman said:

Hi Mary,

 I have built three systems this way, the first, with two aquariums, a 29 and a 20. 40 gallons of growbed. My Twin IBC system is two IBC's cut at the 175 gallon mark. Sump and Fish tank are the same size, this will allow a 2 to 1 growbed to Fishtank ratio. The third system I built for a friend is a 150 gallon fish tank, 70 gallon sump and two 50 gallon rubbermade growbeds. The reason for the much smaller sump is that Franklin didn't have room for more beds. We maxed the space he has and he runs his system with minimum growbed filtration. He has had 30 tilapia in there for nine months without problems. ( This is twice what I recommended but they are still doing well ).

  The main consideration in sump size is how much growbed you need. A  big sump is better in my opinion. It will allow the most variability if you later want to add to the system.

[Murray Hallam]

Hi Mary,
The negatives you have read come from one source only and they are by someone who has not built or run an AP system utilising CHOP 2 methodology.  We have been running CHOP 2 systems for just over 18 months, one system being a medium sized commercial build we carried out (combined raft and media system).  So we KNOW it works and has many advantages especially in the plumbing department.

If we consider CHOP 1, the water is pumped from the sump back to the fish tank and that water then runs back to and through the grow beds by gravity from the fish tank.  The water comes from the bottom of the fish tank, up and out then down to the grow beds. This has obvious benefit of keeping the fish tank always full no matter what.  CHOP works better if the pump is up sized just a bit to make sure there is good flow of water through the FT in order to lift the suspended solids up the standpipe and out down to the grow beds or sump.  This is much more easily achieved using CHOP 2 because we can pump a lot more water through the FT and back down to the sump by gravity. Meanwhile the grow beds are doing their thing processing the water.
Many AP practitioners operating CHOP 1 bypass some of this extra capacity back into the sump to provide aeration in the sump. (remember the pump is in the sump not the FT)
.
The volume of water that can be processed through the grow beds is limited or regulated by the auto siphons, or in the case of a timed system, by the timed pump cycle. The filtration action is being carried out by the grow beds and they are processing the amount of water that is delivered to them. They cannot process any more water that can be passed through them. (obvious I know)
All we are doing with CHOP 2 is delivering excess pump capacity back through the fish tank again, creating a second loop if you like.  The water being sent back to the FT will be partly filtered, partly not.  All the water in the system will pass through the grow beds (filters) at the rate the grow beds can handle the volume of water and be filtered no sooner or later than it would have been anyway.  In the meanwhile any additional pump capacity is being used to circulate water through the fish tank making sure that the suspended solids are being lifted from the bottom and sent to the sump.

The claim that the solids are being munched up and sent round and round, hurting the fishes eyes and turning into soup, paints a picture of great big lumps of fish poo out of control banging around in the system. It is just not true.  If you have that much fish poo in your AP system best you quickly lower your fish population, feed less, add more grow beds or add some serious filters ASAP.

Fish do well when there is a lot of water movement in the FT...they love it.

It is assumed that there is no additional solids filtration in the system anywhere, although to add a stand alone solids filter of some sort is very easy using CHOP 2 methodology.  Simply create another loop in the system and/or deliver water from the pump (in the sump), to the filter then on to the FT, or on to a raft bed then back to the sump or FT.  All that is requires is a few more fittings and some pipe and job is done. You can disconnect or reconnect the filter easily for servicing, or add or disconnect additional raft beds if you want.

The beauty of CHOP 2 is that the water is being delivered to the grow beds, fish tank, (and stand alone filter if you like) at pump pressure which makes things work so much better, makes the plumbing easier and makes the water flow control easer and more precise.

Water flows by gravity out of the grow beds to the sump, and out of the FT to the sump.

Some comments have been made about the use of two pumps in a CHOP system, then it is not CHOP anymore.  We sometimes use two pumps just to provide redundancy.  If one pump dies, then there is another to take over instantly (bit of clever electronics). It is still in essence a one pump system.

Sorry about the long winded reply and I hope I have made it a little clearer. (not worse).

Murray.

Mary Hundley said:

I have read several negatives concerning the CHOP 2 system design (not on this site by-the-way) and the problem of large solid waste continually pumping through the system, breaking down, and absorbing large amounts of oxygen along the way as it decomposes.  What if a floating filter system was placed on top of the sump for the water to drain through to clean out the larger particles and changed and cleaned as needed?  The idea of the constant height of the water level in the fish tank is very appealing and the CHOP 2 system seems to address it better than most.

Sylvia Bernstein said:

Hi Gene.  In Murray's blog post about these systems he goes into the advantages of the CHOP 2 over CHOP 1 - http://aquaponics.net.au/blog/aquaponics-chop-mark-2-operating-system/.  Seems to me it is mostly about having more control with separate pumps to the grow bed and fish tank.  An elegant solution, but CHOP 1 still works great as well.