mattyoga

2 x IBC coolroom heated RAS for Barra

20 posts in this topic

I'm in the initial stages of putting together a RAS system for barra, housed in an enclosure made of 150mm coolroom panels.  I'd welcome critical design review input for it.  The layout is attached.   Basically 2 x 1000L IBC FTs, RFF (200L barrel) + MBBR/Sump combo.  Solids would leave the RFF to an external MT.

 

My first design quandary is whether to have a dual drain setup from the IBCs. The IBCs are 1000L approx, so I want to be pumping 1000L through each IBC per hour ( or should I design for much more??). 

My calcs show that I need 500L/h to avoid settling of solids for 25mm diameter pipe. So if I split the flow so that 500L/h comes from the bottom via a SLO, and the other 500L/h is taken near the top, I would need to have a max SLO diameter of 25mm... which seems quite small.  What do people think ?  This is based on the formula:

 

V>SQRT(gD)0.58

Where:
V=velocity (m/s)
g=9.81m/s2
D=internal diameter of the pipe (m)

 

as provided by Stuart Chignell on the BYAP forum.  

My calcs also suggest I need around 9cm of head to drive a flow of 500L/h through 3m of 25mm diameter pipe with 2x 90 deg bends, 1 ball valve and 1 exit. 

My concerns are, with a square IBC tank will the pull of 500L/h through the SLO be enough to pick up all solids? The dual drain has the advantage of doubling the residence time in the RFF which should improve solids removal, though if they don't get sucked out of the IBC, thats not much use!  (2 x 500L) into a 180L barrel gives residence time of 11mins.

Other option is to just have a single drain SLO, running at 1000L/h, and this would need to have a max diameter of 33mm to aoid settling. If I went with a 40mm SLO, I'd need a flow of 1643 L/h to ensure no solids settling. This would mean though that I'd be putting 3286L/h through the RFF, giving a residence time of 3.6 mins.

Would welcome any thoughts you have on this proposed design... I'll be seeking input on coolroom panel construction later - as can be seen its going to be a tight fit!

 

 

 

 

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One question I have, is how much light will the barra need?  I will be trying to enclose the system and make it as air tight as possible (external air will be pulled in for airpump), so it will be pretty much pitch black in there.  Would a small LED light strip suffice, or is that unnecessary? Would the change from total darkness to bright light upon opening the top stress the fish?

 

I would put a separate heater in each tank, which would provide redundancy.  

 

I would also have two pumps in the sump, one running off a trickle charged DC battery to provide redundancy in the pumps and also bleed of some of its output into the ST/MBBR via a venturi for airation redundancy and power failure. Air would be provided by a separate AC air pump to MBBR and FT's.

 

... Although given the low head nature of the design, I wonder whether a better approach is to just have larger pumps and use venturis all round?  I have the impression from online discussions that Watt for Watt, airpumps achieve more aeration than venturis.

Edited by mattyoga (see edit history)

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Don't do 25mm SLO's... read the forums.. everyone that has done so has had to redesign... ;)

 

P.S.... fish don't really need a lot of light..

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are those problems for dual outflow setups?  Is the problem due to tanks overflowing?  I would have a 40mm overflow at the top of the FT to deal with the other 500L/h of flow (or more if I increase turnover).

 

I take it from your comment that they do need some light then?

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Wouldn't be dual SLO, one bottom drain (SLO) and one top outflow - bottom goes to RFF (which then goes to MBBR), top goes straight to MBBR.

 

Found this post from Paul saying 25mm SLOs work at up to 1500L/h

http://aquaponicsnation.com/forums/topic/8198-solids-lifting-outletoverflow-what-works-whats-voodoo/

 

I'll draw up a flow diagram....

Edited by mattyoga (see edit history)

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Heres the flow diagram,

 

I've only shown one pump, though in reality I'd have two pumps each with two lines to each fish tank, so each line would have 500L/h flow.

 

My calcs indicate that for 25mm pipe at 500L/h the dynamic head is quite low (around 10cm for 3m of pipe with 3x 90 deg bends, a ball valve and an exit.).  However when the flow increases to 1000L/h that dynamic head becomes 35cm.  Those calcs do show that 25mm SLOs would become an issue if trying to put lots of flow through them as people rarely leave 35cm of freeboard above the SLO.

 

The top outlet is sized at 50mm, which allow for all the flow to go through that to cater for the RFF being offline for cleaning etc.  My calcs for that indicate its good for around 2800L/h with a dynamic head of under 10cm)

 

My concern with using a 40mm+ SLO is that with low flow rates, solids may accumulate in it.

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Ryan Chatterson bought up an issue on BYAP with this proposed system in that dual drains and air stones in the FT don't work well together as the air stones create currents that stir up solids that are then drawn up by the top water take off point.  

 

Though I seem to recall that in Paul's home RAS he had one line going straight to the MBBR (from the top of the tank) and another going to the RFF and then MBBR (from the bottom of the tank).  However, I think he did the whole thing without airstones and just used Venturis. Can't find any articles on the Earthan page ATM however.  If you are reading Paul, is my memory correct?  So I could either add venturis to the FT and MBBR, or as an alternative would it be sufficient to add more airstones to the MBBR?  Not sure if this approach would give as much oxygen saturated water to the fish however as the MBBR may consume it.

 

From Pauls SLO post linked above - perhaps I should be designing for 1.5 x tank turnover.  

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I have similar setup and headloss is greater than your calculating. Its a difficult thing to get right under gravity. Calculators are based on having pressure to overcome some issues like trapped air.

Also 25mm will clog and cant really be cleaned, you get a bioslime build up.

 

Firstly an IBC with Barra will need 1000lph minimum EACH, I aim for 1500 lph each

At this type flow it will remove all wastes well, I have used a small wave maker pump to promote swirl sometimes when fish are small.

Much bigger pipe or lower flow will build up a bit, but easy to clear by increasing flow.

Bypassing from top as drawn will reduce self cleaning dramatically, this is a really big deal if you cant get dirt out easily.

 

I use 50mm SLO and 300mm mort tray, far easiest way to capture escapee's. Still needs coarse mesh until they are quite big

Headloss through filtration and MBF will be around 10cm using all 50mm pipework. (plus some 110mm) This filter setup is a key flow constraint in my setup.

50mm DWV pipe works well and is cheaper than pressure PVC

Always try to have pipe penetrations above water level or if it cant be then as high as possible, less head means less chance and smaller leaks also if something dramatic happens, fish will live

Be aware of weight in pipes filled with water, supporting them on ground is often easiest.

Fit full diameter screw caps on ends of pipes so they can be flushed and a brush pushed through.

I am using gravel beds but can bypass from second pump similar to your design at night to conserve heat.

 

There should be some old posts here on Mega bin system. Mine is upscaled version and as basics are done well it works

I have altered incoming water plumbing sice these pics, I use 25mm tap now as had to equalise flows and it now arrives under lid which cuts down algae and leaves getting in

 

post-854-0-64182200-1422595365_thumb.jpgpost-854-0-30051400-1422595551_thumb.jpgpost-854-0-33368600-1422595622_thumb.jpg

Edited by jet (see edit history)
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Thanks Jet, that's priceless info.  Whereabouts in NSW are you - do you have to heat much to get the barra through winter?  Perth winter is too cold to get through without any heating - I've seen my tanks down to 10 degs in winter (though that was pumping through GBs at night), hence the need for good insulation and heating.

 

How many barra do you have in each tank?

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Jet,

 

Are you using the black material around the IBC tanks to block sunlight, retain heat perhaps with an additional covering for the top when necessary, or both?  What material is it?

 

Thanks!

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Black material is cheap poly garden bed stuff - one roll does each IBC. its doubled up and only just now beginning to fray a little

Id probably use heavier EPDM liner or similar BUT it has worked pretty well.

From experience IBC arent made to last, after a few years in full sun the plastic will crack. Under greenhouse light Id say even less time.

These were already reused a few times so were bit unknown.

Mainly used to limit algae growth, some argue it isnt a problem but it builds to a thick layer and flakes off so I try to minimize it.

I use a broom every 6 weeks or so and it is sucked out SLO,

You will need a good lid and I have fences in the low places on the top as fish get out.....a lot.

 

Im in central NSW, our winters are too cold for Barra but I did have a go with a batch last summer. Started a little late then pushed on with heating, eventually and pretty dramatically they got disease and died. Should have pulled them out smaller and earlier. Water wasnt that cool, like 12-15 deg.

Even our hot summer wasnt consistent enough for them. Odd cool night and few days under 35 saw them off food.

Due to cost of the fingerlings I may leave it a while before trying again.

I had 20 in each tank but have run 35 trout in each before. Really need to have solids and water quality sorted and super reliable before shooting for these numbers

Heating is a very difficult thing, I tried many things, gas HWS with exchanger coil was the only way which worked but was expensive. Really need to have in dual skin greenhouse AND heating to even get close to keeping it warm. Even without growbeds, tanks lost all the heat generated overnight.

 

Another point is that Im using a fixed bed media filter too, whilst swirl types work they dont caputre it all. K1 media ~ 600mm deep does a good job. I use air to clean out then drain next day

A little surprising but the 3 blue drums work pretty well. Id love a cone based drum like youve drawn but not sure its worth the cost/effort.

Edited by jet (see edit history)

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Barramundi, assuming that is what you mean by Barra, seem like a royal pain in the butt.  Do they like their water temps boiling?

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Yes, barra are barramundi. Ideally 26 degs, will not eat much below 22, may start to fall off their perch below 18.

Taste pretty good though, and since tilipia are not a legal option here, it's either them or silver perch, and I'm not that enamoured with them on the plate plate.

With the Mort trays, do you have to clean the solids out of them daily, or do the solids move through them and onto the rff?

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Dont have to clean daily, floor of tray just builds up a bit if you dont

Once a week is often enough

obviously thats when fish are big

 

Auto feeders was the other major improvement I installed, feeding 2 or 3 times a day evens things out a lot.

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Got high quality ones from US 

They run on 12v and use timer to trigger set feed runtime

Also rated for outdoors.

Fish tend to splash and send water up into machine, need one which can handle this

 

Seem to be a heap more around now but got doubts on quality and you will need one with few kg capacity and to handle large material - like cat feeders

Aquarium types designed to handle flakes or very fine stuff.

 

Here

http://www.superfeederstore.com/

They are very good to deal with and will sell without timers etc.

Freight is a killer

Edited by jet (see edit history)

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A lot of the "pet" feeders will work fine with larger pellets... but fail miserably with anything less than 4mm

 

Have a look at the "Cloverleaf" feeders... ;)

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Thanks John, They look the shizz, though will probably be too tall for my application as I won't have much head space above the tank. 

 

On another note, does anyone have any idea how much weight a coolroom panel will support?  eg will a 150mm thick panel be squashed by 1000kg of IBC on top of it?

 

I found this link which sites 10-60psi for EPS

http://www.epsindustry.org/building-construction/compressive-strength

 

So a 1000kg IBC cover 1m2 or

 

1000kg * 2.2lbs / (39.4" * 39.4") = 2200lbs/1552 inch2 = 1.4psi

 

so hopefully I've got at least 7 times safety margin 

:)

Edited by mattyoga (see edit history)

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