Backyard Aquaponics
A place to discuss aquaponics

Ok I will try and explain just how water pumps work here, water pumps in at 600ltrs per hour and is sucked out from the bottom of the fish tank. The sump tank is also a 700ltr tank. Now why the water temperature change between the two tanks? I have a split flow system.

Now water on the bottom of the tank is cold. Water on top off tank is warmer. Water from grow beds adds heat during the day when the sun shines on them. But at night they are reduced in use as it gets cold at night. Not good for fish!

that’s why I use timers to adjust the time off the pump and help with water flow.

Now as for my scientific results. The water temperatures in the fish tank were higher when the water into the fish tank was from the top. When the water under pressure below the water line to the base of the fish tank. The water temperatures changed from 2degs higher than sump tank to 2deg lower in fish tank. Overall that’s a 4deg change just by changing pipe flow? This result is day and night. I am not saying the same results will happen in your system. But they have in mine!

Now if and when I talk about my system, rather than talking to others about their systems. I cant see how your systems could be off any relevance? If you are also running two IBCs and growing Barramundi in Perth. Then please add advice here.

I'm sorry.

How many times?

Keep writing it until you learn.

Just don’t mention a filter?

Providing you have certain weather conditions I could not count out evaporation as an effective method of lowering water temperature. Also if you have a clear shot at a clear night sky you could dump heat into space using shallow trays or panels with appropriate heat exchangers.

I used yesterday's temps to experiment a bit.
35c ambient and 20c water:
- I put 4l frozen ap water in the sump-> lowered to 19.5 for 30min and went right backup.
- put a coil of air hose in a cool box with iced water and run air stones through it. --> water temp kept climbing
- sucked Venturi air from an iced cool box into the sump-> water stayed at 21c until ambient went to 39c and full sun on the gb.
- at 21.8 I turned on the 1kw chiller and 30min later I was down at 19 again.

The chiller set to 19 kept running till sunset and then kicked in again for 10min at 8pm and 19.9.
Next hot day I'll disconnect the growbeds (bypassing them so it's solids filter and sump only) compare to yesterday's readings and monitor ammonia buildup.

How big is your sump Ben?
What cooling capacity does your chiller have at 35C air and 20C water?

I've got 37C air and 25.5C water ATM, but no trout to worry about.

Totally agree. Definitely the most cost effective method of removing heat provided you aren't in a humid environment.
I've got my eye on a small cooling tower and this would be the only way I would try to carry trout thru another summer again.

My sump is 100l, holds the pump and Venturi. The system is 1600l constant height gb. and I circulate 2500l per hour.
The chiller at 35c ambient takes about 1c per hour down. At 40c ambient it only manages to keep a constant of 19.

Very good way of cooling but you need to set things up to ensure that the water is evaporating but the flow is not gaining heat at the same time.

Rather than just draping a cloth in the tank and directing a fan at it some sort of trickle filter, baki shower, cooling tower arrangment can make a difference. If you add the fan and force air accross the wet surfaces it will increase the effectiveness.

Does use a reasonable amount of water though.

Also if you are going to go the route of active climate control doing the control in a space that you can control the climate, ie an insulated greenhouse, will make the battle winnable.

Give it up Stuart you wont win there are to many septics on here

the cooling tower wont get the water below the ambient wet bulb temp.

So if its 30 deg and 50% humidity the wet bulb temp will be about 22 deg C.

if you cooling tower is 80% efficient the water coming out will be about 23 or 24 deg C

the psychrometric chart tells no lies:-

On the up side if you design it right you are also providing good gas exchange (small blower feeding from the bottom sounds the way to go)

Slowboat

Dumping to space (if done effectively) will get you below ambient wet bulb temp.

If anyone is interested in this sort of thing I could go way back in history however try Skytherm House and Harold Hay and ask yourself why you have aircon.
Or there again go camping in the middle of summer in certain parts of WA and sleep out under the stars (and make sure you have a *frack* good swag)

Yep shows the limit of evaporative cooling. Effective but only to a point.

The situation gets even worse if you consider how much a insulated gains in heat. You might have x m2 of evapotitive cooling but if you have a heat collector ten times that size (ie the rest of the Gwen house) you are fighting alosing battle. Rather than active controls you want to start at the passive side of thing s. Reflective screens to keep theheat or in the first place.

I think high rise cooling towers are there to cool the heat exchange units in the conventional air conditioners. So it might be worth pre cooling the air around the back of your freezer, to make it ultra efficient with a tower, then running your FT water through a coiled hose in the freezer, then back to the system like you do with a beer keg and and ice box.