Backyard Aquaponics
A place to discuss aquaponics

all you write is perfectly true, Hex
but a bit contradictory:

would by itself solve all your previous objections
you then only need spacer strips on both ends
maybe (to avoid deflection if surfaces are large or plates thin) combined with some threaded rods fitted through equally spaced holes in each plate with just short bits of hollow tubing cut to size and shoved over the rods between each plate to keep them at equal distance.

this would indisputably leave you with much better performance:
single walls everywhere compared to double walls everywhere with possibly an extra bridge between them which will even more diminish performance if the plates are not in perfect contact with each other.

would actually be an advantage for better performance if the incoming air is warm enough (for heating) or cold enough (for cooling)
It would also be a lot cheaper (surface and thus footprint can be reduced) or give you (at least, since performance is much better) double exchange surface for the same price
and one of both air flows would need much less filtering (important !!!) which would diminish maintenance and performance: cleaning an open space is much easier than cleaning all these small channels.

I'm making this up while writing :
using double sided sticking rubber insulating tape instead of spacer strips would greatly simplify construction and make it all airtight and eliminate the need for clamping...
or even better single sided in two or more layers which will allow for easy dismantling and cleaning but would call for clamping...
... just raving on (my mind never stops searching for better, simpler solutions) ...

so on the whole is is a splendid idea and I will most certainly put it to use, thanks TCLynx !!!

... might even give up on my idea of the beer can heat exchanger I posted before (though I have by now collected the beer cans with much effort )

frank

The fish from the aquarium moved back outside to the main system since I'm likely to need to do some re-arranging soon anyway.

Yesterday the aquarium probably got up to 83 F while the outdoor high was probably only 84 F.
I left the valve open last night just to see what would happen.
Aquarium was about 72-73 F this morning and the outdoor over night low was 64 F.
It remained about 78 F in the house.
Main system was at 75 F this morning.

10:40 am Aquarium system still at only 74 F.
Indoor air temp still 78 F
Outdoor air temp only 71 F
Sunny clear morning though.

Had the out door sump been insulated and the valve been turned off. The system probably would have remained at about 78 F.

12:20 pm
Aquarium up to 78 F
Outdoor air temp 77 F
Indoor air temp 78 F

Well I'm not sure what the high temp today was but the passive drain heater managed to get the now reduced aquarium system (small aquarium and the buckets plus the barrel sump)
up to 86 F
The outdoor air temp is 86 F
Indoor Air temp 76 F

The three little fish in that aquarium are quite happy.

Here is my plan for a thermosypon solar heater.
The problem here is freeze protection. So I am planing to use a standard 3ft. by 7 ft. solar copper collector but mount it inside the greenhouse on the side of the grow bed, under the glazing. A 50 gal hot water heater will live on the other side of the grow bed elevated on blocks. Supply to the collector will pass from the drain valve under the GB to the bottom of the collector. The hot return to the tank will be over the top of the bed to the top of the tank. No pump, nothing outside to freeze and heat available at night when needed.
A small circulating pump and differential thermostat will supply H.W. to a coil in the insulated fish tank. Will use 1/2 inch drip distribution hose for all connections. Only plan to heat one tank with taliapia, 150 gal. Plan to put the sump pump on a stat and cut it out when FT temp falls to perhaps 74 def. F. thereby cutting out flood and drain. Will cover the FT, as required, at night.
If the one solar collector fails to heat sufficiently I do have another that I could hang in parallel. The hot water tank will be pressurized so air should not get traped.
Please share any thoughts or suggestions.

Just to be clear Spirit... you're planning to pump your fish water through your copper solar collector and back to your system...

If so ... don't..... copper is bad/lethal to your fish....

And the acidic nature of an AP system will degrade your copper connection flat out...

Result, even worse/faster affect on fish... and significantly shortened lifespan of solar collector components...

Also keep in mind that supplying the drain from the grow beds to the solar collector might be hard to do "under pressure" without a pump.

+1 for the copper warning.

I have been thinking about how to safely use a thermosiphon set up. Challenge is, a solar collector hooked up to a tank in a thermosiphon system can get really, really hot. Make sure you are not going to cook your fish or plants with the water re-entering the system.

My contemplation of a thermosiphon set up would probably only allow the thermosiphon collector to operate during the day to heat up water in the insulated container and then at night run system water through a coil of tubing placed in the insulated container. That way you could utilize the hot water when you needed it most while not exposing your fish to the copper. Then you could even place an antifreeze solution in the solar collector loop allowing you to place it outdoors if need be without worrying too much about freezing. This could let you keep the solar collector and insulated container at constant pressure without need of a pressure pump. The loops of tubing for heating the fish system could be fed simply with a valve off the pumping for the main system.

Only real challenge I have with the set up is that the insulated container must be higher than the bottom of the solar collector and at least as high as the top of the solar collector. I don't have the best space available to do such a thing since my roof is probably where the solar collector needs to go and I'm having difficulty with the idea of putting a big tank on my roof.

First of all the coil in the fish tank is alluminum. My water runs 8.2 PH in the FT, so expect no corrosion. Also the tubing to it is plastic so expect no galvanic action. supplyl water from the well runs 8.0 PH.
Yes, TXC. The hot water tank will be elevated so it's base is higher than the bottom of the collector. The top of the tank will be higher than the top of the collector. Tank and collector will be under circulating pump pressure (40-45 psi). I believe the only pump required will be to the FT coil from the hot water tank. Thermostatic pump control will keep from cooking fish.
This small a collector thru two layers of glass may not even give 90 deg. F. in the 50 gal tank on a bright day. We will see.

OK... think I've got ya now Spirit... so you're "teeing" off the drain line from the growbed just to fill the collector... then pumping through the alum coil back to the collector... right?

Take it you have some sort of non-return valve between the growbed drain tee and the collector then ... so that this is effectively a "closed loop" to the collector...

No, Rup.....I am teeing off of the hot water tank drain line for the low point to supply the collector. The collector goes back to the top of the hot water tank. Supply to the FT is seperate with pump and differential stat control and goes to the the coil and returns to the hot water tank.

Gotcha... so you're just heat exchanging through the aluminium coil....

Looking to trial a similar thing with a stainless tube exchanger.... when I get the time... and money...