system critique

[done]

Hello,

 

While I've been lurking here and absorbing your knowledge for some time this will be my first post.  Thank you, in advance, for all who share.  Okay, onto my question regarding system design.  I guess what I'm after is your validation of my choices.  First, I have a fish tank (FT) roughly 700 gallons in volume, its dimensions are 4'x8'x4' and it's made from epoxy.  I want to stock it with ~120 Tilapia.  I plan to pump from the FT to six 4'x4'x1' media grow beds (GB), using black cinder media and siphons for flood and drain.  The GB's will drain to raft beds approximately 4'x30'x1' in size.  These beds will empty back into the FT.  There you have it, the circle is complete, though I'd also like to add towers to the system at some point.  I was considering a Sweetwater pump, either the SHE 1.7 or 2.4.  The system site is slightly sloped with a ~1.5' drop over 25'.  I plan to place the FT down slope and pump upslope to the GB, which will drain to the raft bed and from there return to the FT.  Still trying to decide whether or not to cover the entire operation with hoop structures.  I live in rainy Hilo, Hawaii.  But we also get our fair share of sunshine.  Do I need shade cloth?  Do I need to shelter the sytem from the rain?  Okay folks, have at it.  Your thoughts, please.

 

Greg 

[TCLynx]

It might be nice to have a structure over your system from which to collect rain water and to control how much goes into your system.  I don't like to have my systems enclosed in greenhouses anymore though as I've done better with my plants out in the open with just some shade cloth for the worst part of summer here in FL.

 

Sounds like a fairly good plan to me.  The pump on my big system is the SHE ?whatever the middle size is I think.

[George]

That's a nice concept to drain from grow beds to raft beds, then to fish tank.  I'm waiting on my fish tank to be delivered and this causes me to rethink a bit. 

thanks

G

[RW]

Very interesting. Sounds like a good plan to me. I'm currently designing something similar on a smaller scale. 

My rough plan has the fish tank on the top of the slope draining to a sump tank at the bottom.  The pump will be in the sump tank pumping water back to the fish tank and to the grow beds. The grow beds will have a siphon that drain to a raft. Both the fish tank and raft tank drain to the sump. I like the CHOP2 design and am trying to follow it. I like the extra control the sump tank will provide. I admit I have a hard time picturing water flow but i hope it will all work out without too much tweaking.

[Jon Nose]

Because your ground is sloping are you planning to do steps ... so as your grow beds stay level ??

also you may want to consider having the grow beds drain into fish tanks to supply oxygen then have them flow into raft table .... have raft pump up to growbeds .... rumor has it that the fish don't like their water rising and falling ....just something I read some where ..

[David Waite]

Greg I think your system is sound. Mine is along those lines with smaller rafts,5x8 in size. You will need to plan on aeration for your raft tanks. Not sure of your pump volume but with the lift and wanting to do vertical you will need about 2100 gph to have some for backflow to keep your water moving in the fish tank. I am using about 1800 gph and wish it was a little more.

[done]

Thank you for the feedback. 

 

TCL, I like your idea of collecting rain fall from the structure covering the system.  Can you recomend an inexpensive yet quality way to construct such a structure?  You say you use the Sweetwater SHE 1.7/2.4.  Do you feel it is overkill for my needs, those being 700 gal FT, 100 cubic feet media GB and ~100 cubic feet of raft?  Is flooding 100 cubic feet of media grow bed from a 700 gal FT workable?

 

George, I have no AP experience but this design was recomended by someone with a great deal of experience.  I suppose the appeal for me is in the simplicity of it.  Fewer components: no sump, no swirl filters and one pump.  I guess I like simple.  I look forward to hearing more about your system as it evolves.

 

RW, I gave serious thought to the CHOP Mark II design, I still do, but decided on my current design in an effort to keep things as streamlined and simple as possible.  Good luck with your system.

 

Jon, I am working to level the ground where I will place the grow beds.  Avoiding this task is one reason I initially considered the CHOP Mark II design.  I have since decided a simple design with a smaller footprint merrits a little back breaking work.  As to the matter of oxygen, I had planned to use an air pump and stones to the raft beds.  The fluctuating water level in the FT is a concern of mine.  I am hoping the depth of the tank, aproximately 4 ft, will mitigate this somewhat.  If my calculations are correct, the 100 cubic feet of media grow bed will require ~40-50 cubic feet of water to fully flood.  Given that each cubic foot is ~7.48 gallons, that should total out to around 350 gallons on the conservative side.  That means my FT is half empty during the flood phase, which is a water depth of ~2 ft in my FT.  Hmmm, will this work?  Thanks for the insight, something to chew on.

  

David, Yes, aeration is on my list of things to look into.  Thanks for the pump info.  I am having some trouble deciding on the optimal flow.  I want enough GPH to more than meet the needs of the system but I want to balance this with energy conservation.  Can you recomend a quality, powerful (appropriate GPH for my system) and energy conserving pump?  I don't mind spending money on a good pump as it really seems to be the heart of an aquaponic system.  Thanks for your feedback.

 

Thanks All,

Greg 

 

 

 

[David Waite]

Try the specs on the beckett 2500 gph pump. I dont know how much lift you have to overcome . It is a great pump and affordable. I use a beckett 1800 but have less than 6 ft of elev from water to top of towers. Amazon sell them.

Greg Laliberte said:

Thank you for the feedback. 

 

TCL, I like your idea of collecting rain fall from the structure covering the system.  Can you recomend an inexpensive yet quality way to construct such a structure?  You say you use the Sweetwater SHE 1.7/2.4.  Do you feel it is overkill for my needs, those being 700 gal FT, 100 cubic feet media GB and ~100 cubic feet of raft?  Is flooding 100 cubic feet of media grow bed from a 700 gal FT workable?

 

George, I have no AP experience but this design was recomended by someone with a great deal of experience.  I suppose the appeal for me is in the simplicity of it.  Fewer components: no sump, no swirl filters and one pump.  I guess I like simple.  I look forward to hearing more about your system as it evolves.

 

RW, I gave serious thought to the CHOP Mark II design, I still do, but decided on my current design in an effort to keep things as streamlined and simple as possible.  Good luck with your system.

 

Jon, I am working to level the ground where I will place the grow beds.  Avoiding this task is one reason I initially considered the CHOP Mark II design.  I have since decided a simple design with a smaller footprint merrits a little back breaking work.  As to the matter of oxygen, I had planned to use an air pump and stones to the raft beds.  The fluctuating water level in the FT is a concern of mine.  I am hoping the depth of the tank, aproximately 4 ft, will mitigate this somewhat.  If my calculations are correct, the 100 cubic feet of media grow bed will require ~40-50 cubic feet of water to fully flood.  Given that each cubic foot is ~7.48 gallons, that should total out to around 350 gallons on the conservative side.  That means my FT is half empty during the flood phase, which is a water depth of ~2 ft in my FT.  Hmmm, will this work?  Thanks for the insight, something to chew on.

 

David, Yes, aeration is on my list of things to look into.  Thanks for the pump info.  I am having some trouble deciding on the optimal flow.  I want enough GPH to more than meet the needs of the system but I want to balance this with energy conservation.  Can you recomend a quality, powerful (appropriate GPH for my system) and energy conserving pump?  I don't mind spending money on a good pump as it really seems to be the heart of an aquaponic system.  Thanks for your feedback.

 

Thanks All,

Greg 

 

 

 

[TCLynx]

I expect the SHE 1.7 would be a fine pump for you, I think I'm using one size larger on my big system and that is covering the flow for the fish tank to grow beds as well as the flow for all my "extra" stuff like towers and raft beds and NFT and the water plant beds.  There are other submersible pumps that would also work well for you too.

 

It will be a bit of fluctuation in your fish tank but as long as you stock lightly enough that the fish are not being stressed by the reduced water level you should be fine unless you are stocking really skittish fish.  I might hope that your fish tank could be 750 gallons for your 100 cubic feet of media bed so that you were doing 1:1 but you are probably close enough to get by.  At least with siphons you will only occasionally see all beds flood or drain together so the extremes of fluctuation in the fish tank will hopefully not happen too often.