Backyard Aquaponics
A place to discuss aquaponics

I agree Steve.
In theroy my bacteria in the green house should be near death every winter? My water temps will range from the high to mid 30's (-1C), (I have even had Ice this year in my header tank), up to the 90's (32C) in summer. Using the range information on the bacteria it would appear to be a loosing battle with such a wide variation of temps. An advantage is my fish respond to the temp ranges by eating less so an adjustment should be made in the system input, (feed).
I realize I will never get a 9 or 12 month grow out in fish untill I give them some stability, but I dont need to control everything just find the balance I can and adjust.
I will look forward to VB's results if or when takes it on.
I agree Jim using the earth for a sink would add stability in temps, every little bit helps. I think you'd have to go a few feet deep for any effective control though.

thats the key point. and as long as the media doesn't itself freeze solid then th e bacteria will be alive..........

This has been an interesting thread. One of the reasons I set my system up in a shed was because of the quite cold weather in the area i live in. But I do feel that on the surface, it has been made to appear that AP is the "miracle cure", but like all things it needs time patience, loss, and learning. In its simplest term it is like a farm and farms need constant attention and understanding even then sometimes things go wrong. But this forum has been soo helpful. might try this... check forum... OOps no I wont

The only surefire way to kill bacteria is to heat them up too hot.
Cooling them down is a great way to inhibit growth, but death rarely occurs.

This information from an associate who cleans cooling towers. The evils in question: salmonella and legionnaires.

nitrifying bacteria can not survive the freezing process, nor a drying process.

Did you read that in the BYAP Magazine Steve

From what I have read in the forum, systems with newly planted grow beds seem to experience the larest heat related issues. Is this because the growbeds act like a large radiator transferring the solar heat from the growing medium into the water? Has anyone tried to cover their growbeds with something(hession, dacron, similar) until the plants leaves provide enough shade to stop excessive heat synch?
In my current autopot(hydro) system, there are material covers for the pots to reduce evaporation, algea growth, and heat exchange in the pots.

Spot on SMF....

Some back-of-the-envelope calcs I did suggest that for a 1.5 square metre GB and a 1500 litre fish tank, if 100% of solar insolation on a hot day (1000W/m2) was absorbed, it would be sufficient to raise the temperature of the whole tank by 7 degrees. I assume that the actual amount of radiation absorbed would be much, much less than 100% and the temperature might raise by a maximum of 1 deg C due to the "solar heating" effect.

The more worrying thing to me therefore is the growbed (and pipes if they are above ground or buried very shallow) acting like a heat exchanger when the ambient air temp is, say, 40+ deg C. Water is pumped through the growbed, which cools the gravel down but warms the water up.

Any thoughts? If the majority of the problem is due to heat exchange on extremely hot days, then shading the growbed may not be sufficient to combat the problem.

mostly we are using warm water fin fish jimmy. We tend to need all the heat in our fishtanks we can get, with the exception of trout which maxs out in the mid 20s.
If u have a 'reasonable' body of water, (say more than one ibc,) we don't have too many recorded temps above 30C here. With a smaller body of water perhaps there could be issues.

atm i have 2000lts of gb in a gh. Had a lotta hot days over 35C this past 2 weeks (some recorded temps in gh of 46C) . My max water temp has been 25-26C in the fishtanks. I do have 6000lts of water in the system tho, so this prolly has some moderating effect on extreme temp variations.

Think two things act to mitigate the actual take up of ambient heat from the growbeds Jimmy....

One, the frequency of the flood and drain cycles (if sufficient) keeps the media from drying out and in combination with any evaporative effect probably lowers the overall heat transfer substantially....

Two, as the plants grow they effectively shade the growbed media anyway....

Of course if you are lightly (or newly) planted and your flood/drain cycles are spread too far apart then the heat transfer will be closer to the maximum.....

Some people raise the flood level slightly nearer the top of the growbed after sowing seed or planting out.... for precisely the reason of stopping the seeds and/or new seedlings from drying out or being affected by the heat..... just remember to drop the level after a couple of weeks....

Sorry to be picky Rup, but this might be relevant:

Water has a higher specific heat (amount of heat energy required to raise temperature) than any other common material. Also, cold gravel will soak up more heat than warm gravel.

So if you're trying to keep you water as warm as possible in winter it makes sense to cycle often during the day, as long as the gravel is warmer than the water, and as little as possible during the night. In fact, it might be worth waiting until the gravel gets above water temperature, assuming that sufficient filtration, aeration and nutrient removal is happening. In cold conditions, the plants are unlikely to run out of water in this time.

Cheers

Aren't we saying the same thing Steem? ...














.

Hah, mostly...

I was only pointing out that during the day, short cycles will keep the beds cooler, and therefore heat the water more than spread out cycles, which is the opposite of:



Is there anyone who's not confused now?

Ahhhh.... but only if ....






Darn..... now that means we're gunna need a realtime growbed temperature monitoring system that can trigger the flood cycles once the growbed media temperature differential is greater than a pre-determined value for the fish tank water......

Bugger it.... I'm gunna use my thumb and a bit of guesswork.......