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Journeyman

Running Hot and Cold...

21 posts in this topic

I want to have barramundi in my system - they taste great and if the Microponics side of things takes off would be a saleable item.

Barra shouldn't be too hard to grow - but I live in Victoria which makes the water temps a problematic thing. But that pales beside the problem I have of also wanting to grow salmon or trout, which prefer colder waters.

The ingenuity of the AP people in making use of water in a variety of ways is respectable to say the least. I've set up a bell siphon to drain water from a grow bed and it sits, automatically allowing the GB to fill to the right level, then draining it down to about an inch from the bottom, then letting it fill again. It pleased my Science lobe when I first saw a Bell siphon set up.

Ideally I'd like to be able to have one system, with the warm fish tank (WFT) at one side and the cold fish tank (CFT) at the other, but water low requirements are a bitch. Not that it can't be done but if you are replacing the tank contents in a shorter time, the heating power requirements jump significantly.

I'm going to practice a bit at SketchUp so I can present my ideas a bit better than just words, but here is what I have been thinking about...

Note that this would be in a greenhouse, so less affected by inclement weather; I have a 70% shade system for use in summer when it can go above 40ºC and auto-vents that will open if the temp gets too high and close off if it drops too far. I also plan to have the FT's insulated to help keep the temps stable.

I can't see any realistic way to use a tiny wattage heater (sub 150W) that doesn't involve a trickle changeover of the water in the warm FT - replacing the contents of the FT even in a few hours jumps the power requirements beyond what a low-level solar/battery 12V system can supply, and I would rather avoid the exorbitant costs of mains power for heating 1000L per hours or so.

This seemed to put a stop to my ideas. Originally I wanted to have they system as WFT --> GB --> CFT --> GB --> ST --> WFT etc. But all the reading I have been doing suggests my fish would die in the WFT from lack of flow even if I diverted enough of flow from the ST to the CFT. It seemed an insurmountable problem until I read about non-GB filtering.

So I am now trying to get my head around the idea of having an insulated filter attached to my WFT that keeps the water clean. The idea would be to keep it small enough in volume that it isn't a significant amount of the WFT water, and keep the water flowing through it to filter a lot of the waste from the WFT - this should reduce the amount of water I need to push through the WFT to keep the fish alive and well and reduce the heat wastage so it isn't so power-intensive to keep the temp up in the WFT.

I think it would also reduce the amount of GB area I need for the WFT, so I'd have most of my GB area downstream from the CFT instead and maybe a 'tropical' GB downstream from the WFT.

It seems to me that the more I can reduce the flow out of the WFT, the less the power requirements for keeping the water at the right temp. So, if this is understandable (if not please ask) what is the best type of filtering to do and how do I get the water out of the WFT into the filter and back again? It seems to me I can do overflow into the filter but would then need to pump it back to the WFT.

What I am wondering is this... could I overflow to the filter, then have the water gravity feed out of the filter into a Y connector with the feed from the pump in the ST? With the gravity feed AND the flow being pushed through the pipe by the pump, would that be enough to drag the warm water back into the WFT system?

A secondary question is, do venturis work at low flow rates? I'm wondering if, at that same Y join, I could somehow add a venturi to start aerating the water. Alternatively the venturi could go at the point where the half-warm, half-ST water is entering the WFT. Or am I asking to much of passive systems?

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Hi mate,

I am having difficulty grasping what you are trying to achieve and why. Can you break down your goals a little more for me please. Is planed commercial of some form?

Regards

Paul

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Hi Paul... no, not planning commercial. By saleable I really meant having something worth the trade. I like my steak occasionally. :D

OK, to basics I guess. 1 x sump. Pump out to a split system, some (lesser amount) going to a warm system (WFT) and some (majority) going to a cold system. (CFT) Both systems CHIFT PIST.

CFT would be as normal, with 1000L FT feeding to 2 x IBC Cold GB's, Bell siphon back to ST (probably) or perhaps timed F&D.

WFT would have trickle feed in from ST - how much would depend on what it takes to keep the system working. Outflow would be trickle out to a GB. Belwo the level of the outflow, have (preferably) a SLO out to a filter barrel. SLO would feed to bottom of the barrel and up through the filter to outflow back to a Y connection to the line from ST to WFT.

The idea is I would have a low-power heater in the WFT and with everything insulated to reduce the losses, feed warm water to the filter and with minimum loss back to mix with the incoming cold water.

The filter would, hopefully, clean the WFT water enough that I can reduce the replacement of the WFT water considerably, so reducing the amount of constant heating needed to warm the water. The water heading out to the GB would be warmer than normal and (perhaps) allow plants from warmer climes to grow properly.

All this would be in a GH where I could regulate the temps with about a 5º spread.

Assumptions (as I seem them):

1. It is possible to reduce the need for wholesale transfer of water from a FT by using a filter in addition to a GB

2. A Y junction with 2 feeds into one would, with one of the feeds being from a pump and the other substantially gravity assisted from the filter, allow the mixture of the 2 streams as the pump pushes the feed up to the WFT.

3. a low-power source of heat, (say 100W to 150W) applied 24 hours a day would be enough to maintain an insulated IBC at (say) 22º inside a GH - all components of the WFT ssytem insulated to slow heat loss.

4. A GB from the WFT would provide enough cooling so water going back to the ST would not warm up over time, allowing that water to also feed out to a FT at perhaps 16º to 18º

5. Trying to warm a 1000L IBC that is being refreshed at complete changeover in even a couple of hours would be prohibitive in terms of power, even if I could reduce losses from the GB's inside the GH and if the system would warm a bit over time.

Note I am not planning on implementing this straight up. I plan to get a normal CHIFT PIST system running in the GH first. What I am trying to do here is see if my thoughts are (not insane) possible at all so I can make sure my initial set up allows me to do other things without needing to be taken apart and moved around.

I am currently running an IBC FT with an IBC size GB - got a few plants and a couple of fish (2 goldfish about 15cms long) in it to keep it running and keep the media mature. When the GH is ready I will set up and spread the mature media into several GB's to kickstart them and run it for a while before starting expansion ideas.

First of course will be a monitoring stage so I know what the GH gives me in terms of stability and how stable my system is. Planting will be increased as the GB's get set up and then once the first system seems stable I will add some eating-type fish.

Only once all that is running and producing will I look to add the WFT system as an extra. I'd rather not have 2 x ST's so the system would join at that point and the output would split just outside the ST to head off in each direction.

Does that make more sense?

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Yes and no.

Do you think there would be a benefit to have two separate systems (hot and cold) instead of sharing a sump? Is there a particular saving you are looking for by using one sump?

Regards

Paul

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Just a space thing mostly. I have a GH 4.3m x 2.5m (about 14ft x 8ft) Plus I was trying to set it up using one pump to reduce power usage as much as I can once I get the solar/battery system.

Thinking about it, if it was possible, (EDIT: if it was possible to run the warm system on a reasonable power supply) a warm ST could be of use for fingerlings.

Other considerations would be, it seems to me, that the outlet to the filter would need to be lower than the larger outlet to the GB. I'm also wondering if the incoming needs to be lower than that again but I think it should be fine as it would have the pump assist.

Also, I'm not sure if the SLO would work to clear the FT if it is feeding out to the filter - would the pressure in the filter system prevent the SLO from working.

Edited by Journeyman
To clarify meaning (see edit history)

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Another point I'd like to clear up - about the heating side of things. In all the reading I have done so far, the people trying to heat their systems have had, as near as I can tell, standard systems. In other words, they rely on replacing the contents of their FT every hour or so to ensure water quality.

If I was thinking that way I'd have to totally agree with that this would be far too costly to do, and for a while I did. But if the filter system can reduce the need to replace 1000L per hour or so, then I am only heating a much smaller amount of cold water and replacing heat loss from an insulated system - far less of a power drain than continually heating 1000L.

Another assumption I am making is that the need to replace the water in the FT so much is to do with the fish and there isn't a need to have 1000L per hour flushing through the GB's.

An unknown is what kind of flow I would get through the filter and also what kind of filter I'd need to prevent toxics building up in the FT.

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Thanks Paul

Cute and useful little program. I'm tired of Corel.

Journeyman, I'm waiting to see what Paul has to say before I post anything from my angle.

Alexander

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OK, a basic layout for the WFT. The size for the filter (100L) is just a wild guess.

post-6778-13795790145551_thumb.jpg

The idea for the filter is to have the input go to the bottom of the filter and have a screen wire support for the filter material so there is clear space below. This would (hopefully) allow a good part of solids to drop to the bottom of the filter where a simple undo the cap would let them drain.

I might need a cap at the top as well to release air as the filter refills, but hopefully the pump suction where the filter joins the input to the FT would pull the water through?

The outlet from the filter would be at the top, so the water would filter up through the material.

I THINK this would be driven by the fact the water to the filter is coming from higher than the filter. i.e. gravity pressure.

The outlet to the GB would be above the outlet to the filter, and be a large pipe so as soon as the water rose above the edge of the outlet it would start trickling out to the GB.

Pump and filter rates would take some experimentation to ensure water is cleaned and (hopefully) slow enough to reduce the heating requirements to manageable levels.

Hopefully that helps a bit...

@Caca - c'mon now, every little bit helps. :D If this actually works I may just have changed how people AP, so never be hesitant in giving a PoV. When I couldn't find anyone having tried just this sort of thing I could have just figured it wasn't possible, but I sat and worked it nthrough as best I could (so as not to waste people's time) then asked.

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I will go with stand pipe as filter outlet in case of pump stop from some reason to prevent sump overflow and also valve in filter out line for adjustment for preventing to dry out filter or stagnate water.

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The stand pipe would drain the filter out the bottom, right? I was thinking have the outlet high on the filter to allow maximum settling of solids, but a stand pipe would do the same I think. Are you thinking if the pump stops, the filter water will drain back to the ST and empty the FT into it? Or is there another reason for the stand pipe, because I don't think that would stop the draining.

EDIT: It just occurred to me as I pressed Submit - do you mean the stand pipe for the filter outlet should be in the FT? Wouldn't that mean the outlet would be out the bottom of the FT? Wouldn't that man my filter would have to be lower than the base of the FT? I'm trying to picture it, and it seems to me a stand pipe loses the water head pressure of the FT so the outlet water would not be forced back up to the filter.

Also, if that is what you are talking about, I'd still be left with the solids accumulating in the bottom of the FT and having a SLO out to the GB would put me back into massive water replacement.

The possibility of draining the FT using the SLO is a real one I think, but I don't see how I can get around the SLO otherwise I risk having solids accumulate on the bottom of the FT. Is it possible to use the Bell siphon trick and use an air hose normally just under the surface of the FT to cut off the SLO should the pumping stop? The air hose would run down to where the SLO turned upwards and when the water level in the FT drops to the point the air hose is exposed, hopefully the air intake would cut the flow through the SLO.

Would that work?

Also, if the inlet to the filter and the outlet from it are the same size, would I need to adjust the flow? I was thinking I would need to adjust the flow from the pump to replace the trickle feed out to the GB while maximising the filter flow back to the FT, but I haven't thought about needing to adjust the flow through the filter. What is the reason you are thinking of?

EDIT:

@Anybody - if I am talking through my arse here, please tell me. I posted here to find out if what I thought of is possible, so if I am full of it, tell me now please, before I spend a whole lot of time, effort and money on trialling this. I have broad shoulders, and I am amenable to reason, so if I am being dumb here or if there is a sound reason why this can't work, please shot me now. :D

(*grins* I also posted about this over on another forum and got a whole lot of reaction about how everyone else has tried this and it is too expensive in power - but I think nobody actually read what I posted - just saw 'heating a FT' and decided to tell me how everyone else failed. I am impressed that here on APHQ, people are at least trying to understand what I propose and working out if it will be feasible. Thank you all)

Edited by Journeyman
Add to ideas about Caca's post (see edit history)

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Hi Journeyman,

I also posted about this over on another forum and got a whole lot of reaction about how everyone else has tried this and it is too expensive in power - but I think nobody actually read what I posted - just saw 'heating a FT' and decided to tell me how everyone else failed. I am impressed that here on APHQ, people are at least trying to understand what I propose and working out if it will be feasible.

To large measure, these things are driven by the world view of the forum operator.

There are four large AP forums in the world and three of them take a largely fundamental view of aquaponics.....premised on the basic flood and drain system.

APHQ generally promotes a less doctrinaire approach.

Since I influence this forum, and I take the view that aquaponics starts off as a recirculating aquaculture system, the use of filtration is widely adopted. The other forums are operated by people who sell aquaponics kits based on the basic flood and drain model so many of their members accept their view of what aquaponics is about.

Having said that, common sense is starting to prevail and many members of other forums are also using filtration.

Getting back to your proposal, my view would be that it would probably be easier to have a warm water system and a cold water system....rather than trying to have both in the same system. That view is probably influenced by the fact that, at any given time, I have the components on hand to build a couple of systems.....at very short notice.

Gary

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How about this.

FT outline to Solid Removal Filter , then to " T " joint - one line to GB

- second line to " Y " from ST => Bio Filter with heather => FT

Bio Filter (reason for BF is less water change in FT) with heather is to compensate heat loss before FT.

Solid Removal Filter (at your wish) to remove solids before GB and Biofilter.

On second line you have two options: one is to use "Y" joint or, to go directly to sump ( in that case, you lose some heat mixing with a lot cold water).

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May be way off base here, but I remember a chap suggesting something similar a while back while looking for economical ways to heat the system.

He had suggested using a heat pump to heat one system while cooling the other one. Things like insulation, moving bed filters and continous flow growbeds would decrease energy requirements. The cooler system could possibly have the ft or rather large sump buried to take advantage of geothermal heatsink. There would be no need to combine the systems in this type of setup.

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I like thinking " out of the box ". Maybe will work , possible not, let's try.

I mean, Gary was ( still) on "heavy fire" for his belief., did this stop him? No. I respect that.

I don't want only to read tread (solutions) and implement ( copy/paste) good stuff , I want to participate creating one.

Alexander

Cheers

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I've been reading around some, trying to see what is possible and what isn't. I'm beginning to think the heating isn't going to be as much a problem as has been suggested - a guy in Perth (sorry, can't recall his name just now) uses 300W heating to keep barra alive through cold weather/nights - he suggests simply disconnecting the GB 's during winter, which would make filtering a must.

On the subject of warming things, I've sourced some black rubber sheeting at the B for $20p/m that would help in the GH. I'm looking around for insulation to stick between the sheet metal FT shell and the FT, and I'm sorting through a range of heaters that run at 100W or less. I've got a reminder to check into heat pumps - maybe I can use one to cool the trout tank while warming the barra one?

But a reference to Sepp Holzer on Paul Wheaton's page by JohnMc led to the Rocket Stove Mass Heater (RSMH) idea. It's a concept that uses very little wood to generate considerable heat and the exhaust is CO2 (which is plant food, after all) and steam (for a nice humid atmosphere inside the GH) at a little more than room temps.

Seems to me it should be possible to scale something like this (see http://www.richsoil.com/rocket-stove-mass-heater.jsp for details) with a 'bench' running along near the Warm FT (WFT) that would help keep the water warm AND the GH for very little amounts of fuel.

If I lift the WFT up, I could even have the 'bench' from the RSMH under the WFT for better efficiency. With the thermal mass of the stove and the bench, I'd even have some resiliency built in for times I don't get back to stoke the heater.

And I have scrap wood all over the back yard just needing cutting up...

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It's a concept that uses very little wood to generate considerable heat and the exhaust is CO2

Fire use oxygen = low Oxygen in greenhouse , high CO2, so air pump will pump that in fish tank and change Ph.

This will work in GH without a fish, or aeration of fish tank need to be out of GH. It is better to have stove somewhere else and bring a hot air to GH.

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A guy in Perth (sorry, can't recall his name just now) uses 300W heating to keep barra alive through cold weather/nights - he suggests simply disconnecting the GB 's during winter.

Yeah I would lean the other way a little. The small aquarium heaters are only good in small tanks. They "might" get your fish through the cold spells (like the next week on the East coast AU) by giving the fish a very small warm space directly next to the heater. It is extremely inefficent. I have also found disconnecting the grow beds in a constant flow arrangement counter to preserving heat. On the contrary, the gravel grow beds, depending on material used are significant heat sinks and provide greater surface area for heating during the colder months.

On the subject of warming things, I've sourced some black rubber sheeting at the B for $20p/m that would help in the GH. I'm looking around for insulation to stick between the sheet metal FT shell and the FT, and I'm sorting through a range of heaters that run at 100W or less. I've got a reminder to check into heat pumps - maybe I can use one to cool the trout tank while warming the barra one?

I think you will be chasing your tail with hot and cold systems running off the same source which inspired my first few questions. Grow the species that is most suited to your area first. When you have mastered that and eaten your fill of fish, have a crack at another species which may require some environmental controls. These controls do not need to be planned in the original build as they will usually use some form of exchange easily added later.

Regards

Paul

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I got through last winter with 3 - 300 watt heater in a 300 gallon tank. I cut the growbeds off at night and it could keep the temps ~62F when the air temp was down to 30F. I ran the growbeds and the temp dropped to 48F. This was still flood and drain , so continous flow might vary. Water has a heat storage capability of 5 times that of rock, so the thermal mass of the rock is minimal compared to the water , unless you're running at a volume ratio of 3:1 or more. I suspect there is lots of evaporative cooling happening to the flood and drain.

Perhaps have flood and drain on the "cool" system and subsurface flow on the warm system.

I am looking at a rocket mass heater myself. The plan I am considering is putting the tanks on top of the thermal mass that buffers the exhaust pipe. I'm still learning about them , but I have a 16 ft trench I will put the rocketmass heater exhaust pipe and cover with sand. Then put the 2 - 300 gallon tanks I have on top of them. I think the sand will disperse the heat enough to keep the tanks from melting. This is in the idea stage at them moment (trench is dug though).

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Fire use oxygen = low Oxygen in greenhouse , high CO2, so air pump will pump that in fish tank and change Ph.

This will work in GH without a fish, or aeration of fish tank need to be out of GH. It is better to have stove somewhere else and bring a hot air to GH.

Good point about the CO2 - I will have to make sure the firebox has a good air supply. One thing to keep in mind though, is that with the RSMH system, the CO2 is sent through the tubes, so if I vent outside the GH, it will not be adding to the CO2 inside the GH.

Also, it may be something I [i}WANT[/i] in the GH - if I cover the fish tanks and aerate them sufficiently, a high CO2 (comparatively) content will encourage plant growth. It's one of my bugs about the whole AGW debate (Anthropogenic Global Warming) they forget CO2 is plant food and with our population like it is, we NEED that extra boost for plant growth.

So, if I make sure the FT's have plenty of DO, and maybe cover them to prevent too much admixture with ambient air in the GH, the RSMH would both provide a warm environment, heat the FT's AND boost my plant growth.

All this is for the future - as mentioned above, my first priority is to get the basics working. My explorations of the possibilities is more to ensure I don't plan OUT the possible things I want to try later and wind up having to take everything apart just to try other things. For example, one thing I have decided from learning more about how people set up their systems is I will be raising my FT as high as I can get it inside the GH - the better the fall of water, the more I can do.

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Hi Journeyman,

I'm looking around for insulation to stick between the sheet metal FT shell and the FT, and I'm sorting through a range of heaters that run at 100W or less. I've got a reminder to check into heat pumps - maybe I can use one to cool the trout tank while warming the barra one?

My view is that this would make your fish production cost more than its worth.

I have also found disconnecting the grow beds in a constant flow arrangement counter to preserving heat. On the contrary, the gravel grow beds, depending on material used are significant heat sinks and provide greater surface area for heating during the colder months.

This is contrary to my experience.....but I guess it comes down to when you actually isolate the beds. At day's end, the grow beds will (depending on the day/night temperature differential) be warmer.....but that they will lose temperature in the first few hours after sunset. I've found that, if you're going to isolate the grow beds to minimise heat loss out of the fish tank, you're probably best to do it before you go to bed........and then to open them up again mid-morning the following day (once the sun has warmed things up a bit.). Ideally, you'd have this part of a system automated so that you could achieve the optimum outcome with the least amount of personal effort.

I think you will be chasing your tail with hot and cold systems running off the same source....

I agree.

I also share the enthusiasm for rocket mass thermal heaters (if constructed and used properly).

But a reference to Sepp Holzer on Paul Wheaton's page by JohnMc led to the Rocket Stove Mass Heater (RSMH) idea. It's a concept that uses very little wood to generate considerable heat and the exhaust is CO2 (which is plant food, after all) and steam (for a nice humid atmosphere inside the GH) at a little more than room temps.

The rocket mass heater will discharge carbon monoxide (among other things) for some time after you fire it up......so I wouldn't exhaust it inside the greenhouse or you could get.....dead. The other thing is that the exhaust from the mass heater is quite cool so there's no real heating benefit to be had from having it inside the greenhouse.

Gary

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