has anyone used solar pool heaters for heating fish tanks?

Stuart Chignell

No matter what form of heating you use you will need a lot of it. Greenhouses are excellent solar heater all by themselves. If your greenhouse is not staying warm enough you need to first look at its level of heat loss. Once you have done that look at how warm/cool your GH is. If it is still not warm enough (It won't be) then you need to increase the amount of solar radiation you are collecting.

Then have a think: how big is my collection area now?

Oh wait that is my GH?

How much more do I need then?

Answer: Lots!

You can reduce the amount of solar collecting area by adding higher efficiency collectors (eg vacuum tubes) but it is still going to be lot.

Gunagulla

Ronmaggi wrote:

I remember reading that vermiculite does a great job holding heat.

I think you have been reading the wrong material Ron

It has only one fifth the specific heat of water: 0.84 vs 4.18 kJ/kg.K

Using it as you suggest would significantly decrease the amount of stored heat!

Stuart Chignell

Vermiculite can be a good insulator but would only be useful holding heat if it was built around something else that had a reasonable to high thermal mass.

bentaz

Not solar so maybe not relevant here but I am thinking of running a coil of poly pipe inside a compost bin and run my sump water through it for heating with a small pump. Which could also be done with a closed loop to keep the junk and poo out of it.

Stuart Chignell

Ronmaggi

You might find that the compost will cool off too much and stall out.

Slowboat

normanjarvie wrote:

Hi Guys
I am looking at solar heating ideas for my system, Has anyone tried using 12mm or 19mm polypipe?
I am thinking of using the natural rise of hot water, as water heats up it becomes lighter than cold water rising to the top of the FT then a connection to the bottom of the FT draws the cold water into the poly pipe which is in the sun.
The poly pipe is looped from the ground in a continuous rise to the top of the FT thus doing away with a pump.
The only thing is, it will need a controller to close a valve when the water gets to the required temp.
I've used this set up with swimming pool solar panels the only difference is the controller turns on the pump to circulate the water where I want it to turn on an electric valve. Maybe one similar to an automated sprinkler system.
Any thoughts?

It would be possible to use the thermal convection but:- It would need very careful pipe laying to maintain even gradient going up outside in the sun and similar gradient going down in the FT. in the FT the pipe would need to be Stainless steel tube but only a fraction of the length of the outside black poly pipe. And don't forget the header tank to keep the pipe full.

IMO it would be easier to just pump to a nearby roof lay several coils of 12mm poly and put on a timer or thermostat. if the pipe is full ie with a head tank there is no head for the pump to work against, the only loss would be friction so you would only need a small pump.

whatever heating system you use, insulation would be imperative as Stuart said. :thumbright:

daucie rose

Hello Good people,

I'm one who went whole hog last winter building parabolic collectors for my tank.
I had 3 2ft x 10ft mirrors focusing on 1.5 inch stainless tubing.
I even built photo cell tracking so I got a full 8 hr run every day.

Even with everything working perfectly they would only give just over 1 degree temp rise.
But I was losing 5 to 7 degrees each night. So I bought a back pack tankless water heater and
logged in an average of 29000 btu/day heating need.

That means I would need over 900 sq ft . Almost my entire roof

Now I love the building much more than the fish so I'm not in the least sorry I did it but it had no
effect on my propane costs.

The most effective thing I made was a near air tight cover for my tank.

Sorry to be a wet blanket.....Daucie

bentaz

Stuart Chignell wrote:

:banghead:

Ok so I did some reading and I won't mention it again, I promise. :whistle:

Stuart Chignell

daucie rose wrote:

Hello Good people,

I'm one who went whole hog last winter building parabolic collectors for my tank.
I had 3 2ft x 10ft mirrors focusing on 1.5 inch stainless tubing.
I even built photo cell tracking so I got a full 8 hr run every day.

Even with everything working perfectly they would only give just over 1 degree temp rise.
But I was losing 5 to 7 degrees each night. So I bought a back pack tankless water heater and
logged in an average of 29000 btu/day heating need.

That means I would need over 900 sq ft . Almost my entire roof

Now I love the building much more than the fish so I'm not in the least sorry I did it but it had no
effect on my propane costs.

The most effective thing I made was a near air tight cover for my tank.

Sorry to be a wet blanket.....Daucie

Yep.

Stuart Chignell

bentaz wrote:

Stuart Chignell wrote:

:banghead:

Ok so I did some reading and I won't mention it again, I promise. :whistle:

coachchris

We had(recently removed) 2 - 4' by 10' solar heaters for our pool on a South roof. It would get to over 130 during the day during Summer, and well over 100F during Winter. Not sure how that wouldn't work to keep FT warmer...providing the tank was well insulated and covered. By issue that I have is like previously mentioned, you can't just pump the water through the small poly tubes, as they would clog. So you would have to run a prefilter before the heater and then have a large enough pump to pump up to roof or where ever they're located. Not sure if the cost of the larger pump would offset the savings in larger pump? Think I'll just stay with the GH and insulate FT for now. If I weren't in central Fl, I would spend more time investigating.

daucie rose

Hi, Guys

I just realized that I really did you a disservice with my post.
I live in Bakersfield. 106 degrees and no breeze at all. that's normal here.

My tank is built with heat dissipation in mind. Not normal for most people on the forum.
An IBC tank with just a little insulation would have heated just fine.

The main problem I had to really watch out for was clogged pumps.
Without good water flow my collectors would boil and pop the end caps, so there was plenty heat.

Kind of like asking a diesil mechanic to fix a skate board; it might work but it will weigh half a ton.

So, I shall hang my wet blanket out to dry and encourage you to go for it. It's actually easy
if all parts are designed for it.

I shall think twice before speaking next time....Daucie

Stuart Chignell

Don't do that, we need (well want) the input it is just that some things pop up over and over again.

You can heat and cool systems but people so often just don't realise how big a job it is.

jet

I used some LDPE pipe, 1/2" as heat exchanger, just in bottom of drain tank, moved heat surprisingly well to water. I was using gas heating but no reason you couldnt use a pump and move clean water to solar coil of LDPE on the roof.
Water in heating loop is not fish water and so wont clog
Run DC pump from solar panel and you have auto day/night control

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has anyone used solar pool heaters for heating fish tanks?

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