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Can someone tell me the most efficient way to heat my fish tank water?  Thanks  Doc

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  Homemade always wins out around here, but industry can often be a good place to pilfer ideas and material specs from....

Jim Fisk said:

Thanks for the links. Interesting but I think any tinkerer worth their salt can beat those prices by a mile. Solar storage can be very cheap and should be unless you are running a commercial op.. and even then there is the ever shrinking bottom line given our current fiscal crisis which is about to get a hell of a lot worse. I have used rock mass and water mass storage very successfully in the past and will apply that here once again along with cold species for the winter and wood heat bu.

I remember this being a rather interesting, basically solar, technique...

Would require some good planning though...

Now that's a great link. Will have to digest it all tonight. Done digging for this season but there is next season. Thanks Vlad.

I do not have a lot of photos but my tanks are in the ground. I made a treated 2x4 wood frame with plywood on the inside and 2" foam on the outside. Then I attached an R15 aluminum bubble foil to the plywood. Then I attached PEX to the plywood through the aluminum with screws. Then a double liner to make sure it does not leak. I have a zone valve out in the greenhouse with a temp thermistor in the water telling my hot water heater to turn on. My goal now is to make one more Solar Panel to get my fish nutrients in my rafts to warm up about 4 to 6 degrees per day and then I loose 2 to 3 at night so my PEX system is not used as much. I am using only 1 panel now and the propane comes on at night on and off for about 3 hours. By adding the other panel I hope to have that come down to not using any Propane at night except on real cloudy days and snow storms. Hopefully I can gain a few degrees per day and control that so it does not get to warm but I am thinking that 1 or 2 degrees per day increase should be okay. Also I am hoping that the 3 to 5 degree per day shift in temperature will be okay for the fish as well not sure though.

If the temperature shift is too much for the fish then I will not build a second solar panel and leave it with just the 2 or 3 degree increase and let the propane do its thing until I can afford a good wood boiler. I have an experimental double 55 gallon wood stove in the greenhouse that I put in a stainless steel heat exchanger last year and got really good results in heating a 250 gallon storage tank BUT it had to much smoke letting out of the door when I opened it to load. I bought a fan for the stove pipe that I will add to this next and try it again and see how that goes. If I get rid of the smoke then I will burn wood at night in the wood stove. I will get some heat in the greenhouse from the stove and a lot of heat in the storage tank that I will plumb to my propane water heater with a heat exchanger. I keep testing things and trying things all the time.

Hi Joe...I kinda followed the stuff you wrote last winter on your heating exploits (wish you'd post more:)... I've thought about a rocket mass, a wood burning stove, I have a 134,000BTU LPG (propane-butane mix) heater and tanks, but am loathe to use it as the only heat source...I ran into something at the village store they call a "trinjara" here...Basically it burns saw dust...which I have plenty of...

I Googled a bit, apparently they are not to popular in 'the West', but managed to find some info in English...I'll be building one soon hopefully. I like this solution since you can load it up and leave it be for 8-12 hours (as opposed to a rocket mass stove)...

Don't know if this helps anyone or not...but I was impressed at the ease of use and simple construction and the heat generated by 'waste material' by the one I saw here in the village...

Hi Vlad. I set up the propane side of things first and it works great except that the cost of propane is high and who wants to keep buying it.  The wood stove idea came next but the smoke stopped it last year so with the new inline fan I hope to continue using it to heat this winter and create that water storage needed to stop using the propane. If this works good then I will be good on the fish tank heating side of things. Then if I can afford one down the road I will get a larger wood boiler and add that to my propane system. Something that can throttle down and start up when heat is needed. The idea then would be to heat the hot water heater as high as I can without missing that up or just keep heating my storage tank as high as I can and heat exchange that into my system or both. Maybe I can heat the hot water heater to its max and then anything after that goes into the storage tank and third it dumps into the greenhouse water to air exchanger I want to get.

I like the rocket mass heater concept but can't seam to figure out how I can adapt that to my fish tank waters, storage tank water. The overall heat to the greenhouse might be okay but I have a 1500 sqft greenhouse so heating my water is more important than heating the air.

Yeah I hear ya, but just keep in mind that if your water temps are higher than your air temps you'll be in for lots and lots of condensation (which can do a number of funny things) ambient air temps in a GH are kinda important too. 

Have you checked out Rick Stillwagon's pellet stove water (and air) heater? Seems to work real well for him. He's a bit of a craftsman and has begun to sell some of the AP/GH stuff he's been building. Check him out for some ideas...see if you can work some specs for your set and setting...might be worth a shot...

Do you have a link to that pellet stove from Rick?

He has a lot more info on this strewn about in various pages and comments. You could maybe contact him if you have specific questions. He did seem to document his 'test run' last winter, if I recall...Cost to run, temps, volume etc...

Are you rearing tilapia, or something a bit more cold tolerant?

I am rearing Catfish and Yellow Perch and keeping them at 70 degrees. I could go higher but do not want to spend anymore money on propane. Working on Solar panels instead.

With the solar panel I made hooked into my rafts with a small 800 gph pump I am getting a 3 to 4 degree rise everyday. At 6:00 in the evening I am at 73 and at 8:00 in the morning at 69. The propane water heater comes on about 2 to 3 hours in the night. I paid $180 for the materials to build the first panel. I can build another panel for $180 and have a total of $360 to keep the propane water heater from coming on. If I get 6 to 8 degree rise per day then loosing 3 to 4 or more per night I should not have the propane system go on. When I have days like I have had then I will gain everyday a few degrees and then when it is cloudy or winter storms come it will go down and start all over getting warmer.

The biggest question to what I am doing is can my fish handle the temperature swings of 3 to 4 degrees per day now and if I add another panel it could go to 6 to 8 degrees per day. I have 3000 gallons of water in the system and still loose 3 to 4 degrees or more per night. I could turn my pumps off at night and save on the temps because I am sure I am loosing it via the filling of the media beds that are used for bio-filters.

If there is a problem with my fish having to go through stress of the temps going up and down everyday then I would be better off putting the solar panel on the Utility room roof and then heating a water storage tank of 250 gallons and getting that tank as hot as I can during the day and then let the propane system use that hot water with a heat exchanger until it is used up and then go to the propane again at night. Then I would have to see how my 4x8 panel does this way and wait to build another one.

Using the pellet stove would help with heating at night on a on demand way via a pump and thermostat. I am pretty sure by the photos and comments on the stove that Rick is heating the fish water. So the stove is acting like my solar panels but has way more control in that the pump shuts off when the fish water is at 70 degrees. Now the fish water never really goes up during the day, unless the stove is on, but if you loose any temps during the day you could loose a few degrees but that should be okay.

The other thing is if the pump goes off on the heat exchanger on the pellet stove what happens to the water in the exchanger? If it stagnates then the fish water will get way to hot and could boil and then the pressure relief system would kick in but I am not sure I like that so I would need to talk to Rick more about what he is doing for that. If you constantly heat a fish tank or storage tank and the heat gets the tank to where it should not get any hotter I would want it to either stop the burn or go to a dump zone. That can be done again with a controller. Then the hot water is still being used and not getting to hot. I would want it to go to a water to air exchanger and just put more heat into the greenhouse.

I am looking at the costs of the panels at $180 per panel heating the fish water during the day and having it go up and down and not knowing if this is good for the fish verses putting that heat into a storage tank.  The cost for the tank I made was about $150 and need to build a heat exchanger for the tank yet.

Spending $1300 for a pellet stove is okay but having to purchase pellets at say $5 per day is $150 per month or $900 per year based on running it 6 months per year where I live in sunny Colorado. Looking at the solar panels and using the fish tanks as a solar storage tank or going to a storage tank with heat exchanger will cost less than the pellet stove and you do not have to keep buying the pellets. But you are heating the greenhouse with the pellets you are buying and the solar panel system will not be able to do that unless you build some really big setup.

The question then on the pellet stove is how many BTU's will the stove put out per hour and I think it was about 57,000 but I have not seen anything but conversations on that. For my 1500 sqft greenhouse I would need 2 or more depending on the exact BTU output. If it is less than 57,000 per hour then getting 4 would cost me $5200 plus fuel costs of $600 per stove. I have been quoted $4500 for a 250,000 BTU per hour wood boiler that stops and starts and I am surrounded by trees.I think the pellet stove would be great for smaller greenhouses.

Rick if you read this but if the stove could have an auto start and open and close the pellet shoot on a on demand basis now you have a setup that during a day could come on when needed and shut down and save money on fuel. In a small greenhouse it would make since if that could be done so if the temp reaches a set point desired then you save on fuel again at night as well.

Vlad Jovanovic said:

He has a lot more info on this strewn about in various pages and comments. You could maybe contact him if you have specific questions. He did seem to document his 'test run' last winter, if I recall...Cost to run, temps, volume etc...

Are you rearing tilapia, or something a bit more cold tolerant?

Hey Joe,

As far as losing heat by filling and draining your media beds...why don't you try running them constant flow/constant flood to get rid of the 'heat sink in reverse' phenomenon..?

I have to warn I'm not a fish guy, and will definitely be subjecting my carp to much harsher conditions (temp swings) than you...There are a lot of knowledgeable people on this forum (much more than) I when it comes to fish, and what they will put up with. Different species probably react differently to different environmental stresses. Mr. Kellen Weissenbach from White Brook Tilapia Farm stands out as someone extremely knowledgeable on the topic of fish, and of course the usual suspects...TC, Rupert, Nate Story, John Parr. 3-4F degrees doesn't seem bad, but I'd just be talking out my ass on that one...

A dump to air exchange is a real good idea to keep from making fish stew, and still use the heat to raise air temps...See how Rick handles that. He seems to have elegant and practical solutions-o-plenty...I heat my house with a would stove, pump, and radiators and have installed a number of safety mechanisms, but an air/water wood or pellet stove for an AP greenhouse would be an other beast altogether...  

Whats stopping you on the wood boiler option you there a catch to that?

I have to save up for it not enough cash yet.

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