Backyard Aquaponics
A place to discuss aquaponics

the amount of planning going into your project Doug should help with many of the problems we all come up against. Well done. I tend to charge in, then clean up the mess due to lack of planning

Luckily you have Axl to guide you through these trying times - except when he is on one of his fish safaris (by the way, has he caught Pav yet? )

no not yet, we were too busy yesterday washing gravel and cleaning an entire bottle of bright red nail-polish off a 3 year old and the house

Ah! - children playing "grownups" games

did you try using pee to remove the polish, mightn't be effective in cleaning off nail polish but the smell will deter the kid from trying in future (well that's the theory , in practise, it just makes the kid more street wise )

This has been a great site. I have had my system going since last summer. Being in Florida I have different problems, however, winter serves to show problems with cold. This year so far has been mild, but you never know, spring can get cold. I am raising tilapia. They can not handle anything under 50F. I have a 9' X 3' tank. After this much time I am about to take the things that I have learned and redo the whole thing. I am going to bury the tank half way. My tank is wrapped with stryo for insolation, and covered at night with 2 400W heaters in it. This kept the water to 58F when the temp got to 46F at night. If it were not for the sun warming the water during the day, I may have lost fish. By burying the tank the natural ground temp will help, with the sun during day keeping the temp up and I will be going to a gravity return instead of a sump pump return. I am adding 5 more grow beds this way. I am building a green house with pvc pipes. The top will be 6mm greenhouse plastic and 30% shadecloth on the sides. Also a shadecloth pull below the top to be used during the hotest sun times. The higher the peak the better to allow for the heat to raise.
There are so many ways to start. I am glad I started small and will grow with each change. As you make your plans the group here is great to help. I also will be posting new changes with in a short time to get better ideas. Enjoy your time with AP John.

Joyce: I think you could skip the heaters with a bit of care - you'll need to stockpile heat during the day and insulate better. A 9' x3' (x what?) tank should easily contain enough heat to last a night.

Sorry, I thought after I posted that it might be confusing. It is 9' round and 3' deep. Well, that's what I thought too. Florida nights can get down into the high 30's low 40's. This year the coldest was 46F. This only lasted 2 days. I am concerned that with such a mild winter that the tank did not stay warmer with a 1" foam around it. The foam and covering it at night helped, but this is why I think I will bury part of it, also to lower it for the new grow beds and gravity feed. For next year I will try some of the ideas you guys have in solar heating. The fish are happiest at 80F.

evaporation = 2.2MJ/kg. That's where your heat is going.

So what is being said to John, get a deeper tank with smaller radius?

njh, I just noticed your age! I'll bet you have seen a lot of change in Melbourne in the last hundred years.

Here's to the next hundred!

I am going to continue this on my thread.

[quote="Doug_Basberg

I also am installing a heat exchanger that I am designing from copper tubing. The cold here made me decide on antifreeze in the exchanger. So it is not tank water in the exchanger pipes. I will use 4 ten foot 1/2" tubes in the tank and six 1/2" tubes in full sun. A very small pump moves water to add (or subtract) heat from the fish tank. .[/quote]

Doug,
Thanks much for the insight concerning the spacing between the layers of lexan. I may change my plan based on what you said. Are you building your own greenhouse or using a kit design?

Please elaborate on your heat exchanger. Pretend that I am ignorant, (which isn't much of a stretch) and explain how it will work and why it will work. If I can wrap my mind around the concept it may just be something I will want to add to my plans.

The fish won't like the copper

I wasn't suggesting anything specifically, but it is worth considering covering the tank with something (greenhouse?) and regulating the dry air input.

I doubt there will be much copper migration. It certainly doesn't affect tap water much. I also doubt that such a design will be very effective: 40 feet of 1/2inch = 0.24m^2. The boundary layer in water is probably around 0.2m^2 C/W, so you're looking at maybe 2W / C heat transfer rate. For comparison, my 30m^2 car radiator with forced air and water gets about 450W/C.

Melbourne has changed a lot since I was a kid, I remember the milk cart, and the introduction of electrical lighting. mobile phones were a lot bigger too (they used to need a barge to move them around).

Yes but as has been pointed out previously, tap water through copper pipes only occurs once - fish water through copper pipes is continuous and each little bit of CU continues to accumulate