Backyard Aquaponics
A place to discuss aquaponics

Thank you really good informative info, will be looking at redesigning our heat transfer system now.

Excited to see how you go with the summer cooling.

Guna I love your scientific recording. I've never been any good at crop rotation cause I never end up writing down what I planted where and even if I do I never plant what I'm supposed to where I'm supposed to. I envy your discipline.

Ozgal I love your avatar!

A bit of cooler weather during the week, combined with some experimentation on the system, dropped the water temperature down again, causing the fish to lose interest in eating much, but now the water is warming up again they are back to eating lots. Running the heating circuit pump helped bring the water temp up from 7.5C. Only 35g eaten on the 22nd, but 130g yesterday.



Recently I've run the pump with a 15on/45off cycle overnight, but on the 20th I ran a test: I ran the sump pump all night, which lead to a significant drop in water temperature of 5 deg overnight. On the 21st I ran the pump with a 5on/175off cycle, although the 30 min run at 6am dropped the temp quickly just before sunrise. On the 22nd I ran 10on/170off until midnight, then 10on/50off until 6am, and since then it has been running 10/50 all night. I only have a 560lph air pump in the FT ATM, and didn't want to risk low O2 levels overnight, so didn't do any tests with the pump off all night, as the returning water probably provides more oxygenation than the air pump while the pump is running.
It is clear that overnight water cooling increases with pump run time duration, so as the weather warms up to daytime highs in the mid 20s, I'll probably increase overnight on times if the minima is likely to be around or below my desired water temperture.

A couple of pics from yesterday:

Peas going crazy, in need of more support after they fell over on top of everything else in strong wind the other day




The enemy- sap sucking aphids on the wheat, which has just started to develop heads of grain.




So far I've fed 4kg of 3mm pellets to the trout, although a few hundred grams of that wasn't eaten, mostly from early on when they were a bit unwell. To date I've harvested about 3kg of cauliflower and over 8kg of rainbow chard and silverbeet, and the chooks have eaten a lot of cauli leaves and a few cabbage leaves as well.

The end of winter had temperatures more like late spring, and it looks like continuing well above average temps, so I've started doing some calculations and experiments to see how well my planned cooling system might work to keep the trout comfy.



Just shading the E side of the GBs to keep the morning sun off them has an easily measurable effect on the temp of the water returning to the FT. I think that minimising heat gain during the day will be quite an effective measure. I'll probably start running the small refrigeration unit to circulate cold water around the outside-of-tank piping system within a week as well.


Several heads of wheat have made an appearance, at this rate 2 crops of wheat per year would be doable I think. I'd really like to try some rice, but will have to source some organic grain that hasnt been processed in any way.



The peas I planted 2 or 3 weeks ago in GB#7 have mostly appeared, despite the age of the seeds- expired in 2009! In GB#8 (the outside one near the FT and ST) I've planted 3 tomato seedlings, Apollo Improved Grosse Lisse, and Big Red, and a few melon and pumpkin seeds. I've removed the brocolini, the heads were disappointingly small and went to flower too quickly. We ate some raw, and the chooks enjoyed the rest.
pH was down to 6.83 in the FT this morning, so I might add some more shell grit.

I picked another good sized cauliflower yesterday, as well as heaps of rainbow chard- 9 bunches sold to the market and some for ourselves. To date the trout have eaten ~4.7kg of pellets and I've harvested >16kg of food, plus a few kg of leaves for the chooks.

Love it!

The greenhouse view as of Saturday evening

With afternoon air temperatures like I have experienced in the past week more normal for late October, it has been a struggle to keep the FT water below 20C, especially so with the consistenly unusually warm nights, due to cirrus cloud cover. I've been running the 24V refrigeration unit to cool water for circulating around the tank, but with water coming back from the GBs at ~20C in the afternoons it isn't really keeping up, partly because of a lack of insulation. I've been adding a few kg of ice as well in recent days, and have so far managed to keep the FT to a max of 19.6C. As you can see from the graph, my efforts have had some effect- the water temp is coming down relative to average diurnal air temps.
The next few days are forecast to be in the high 20s max, so I've put one of our spare chest freezers, normally used as a vermin-proof chook food storage container to use as an ice making machine. I've done the calculations- it takes a lot of ice to cool 6000l of water by even one degree, but thats ok, as I am just trying to reduce the afternoon peak water temperatures. I also need to find some suitable insulation for the GBs, the aircell insulation I was planning to use will fall apart due to the UV radiation, and I don't want bits of plastic everywhere, so I'm looking at other alternatives that wont cost too much, wont be attractive to birds for making nests, or look too untidy.



The water has become rather brownish in colour, becoming less transparent each day this week, possibly related to me removing the polyester fibre filters I have under some of the GB water inflows, and maybe due to the warmer temperature, although only minimal sunlight can get into the FT. The water is becoming increasingly acid, so I added 20g of KOH yesterday evening, and might add some more today.

I sold another 5 bunches of chard yesterday and have picked a couple more caulis, the chooks have been loving the leaves from them- I pick a few at a time in the days leading up to harvesting the cauli.

I'm becoming a bit concerned about the feed situation, I'm still feeding them 3mm pellets (with a few 5mm mixed in this week) and have large bags of 5 and 7mm pellets still to go, and the water is getting a bit too warm, too early in the year. At this rate I wont be able to keep them long enough to eat anywhere near all the pellets I have. When I feed them in the mornings I can feel the size of their mouths on my fingers, they are certainly mostly big enough to eat the 5mm pellets, so I might start mixing a lot more of them with the 3mm size shortly.

Gunna my trout have increased their feeding by about 50% this week on top of the 100% since I added the airstone. Maybe they will continue their feed intake at this rate and you won't need to worry?

Are you running your pump on solar? I'm trying to do a plan for the primary school installation and would preferably like to use solar but can't seem to find one large enough (1500l growbed so was looking for a 4000 l/hr pump. The panel doesn't need to work continuously though on a flood n drain. If I get pump, plus inverter, plus battery and controller I may well blow the budget and don't want to leave a legacy if any component dies within the year. On the brighter side silvers can apparently withstand temps 2 - 35 deg. No freezer box required!

I'm on a $1400 budget. Going to scrounge for freebies but at this stage its all I have to work with.

Yes, all running on solar, as part of my off-grid house system with Lithium batteries. With everything running overnight in recent days- 260W pump, 250W fridge unit + 90W circulation pump- it certainly chews through the kWh!

My feeding rate has increased somewhat too, although it is up and down a bit. They were up to 160-170g a few days ago and munched through 200g yesterday, but I've cut it back to 130g today due to the brown water and high temps.

I've PM'd re solar for your school.

Lithium? Nice!

Gunna, brilliant looking system!! Something like this is where I'm aiming in the long term. Thanks for your detailed and scientific approach to your thread!!i have learned so much from just reading through..

Keep up the great work, I'll be subscribing for future updates, hopefully the weather settles down soon

Dave

Thanks Dave Yes, I'm hoping for more like average temperatures so I can grow my trout out to a decent size. The cooler weather this week is still a few degrees above average for this time of year. I just measured FT water at 15.3C, so I'm happy with that. Nevertheless, I'm stockpiling ice to get me through any brief hot spells, I've got about 70kg of of it in the chest freezer now. Lots of solar power available, so I may as well put it to good use and save the energy in the form of ice for a rainy, err I mean, hot day

If I had any spare cash, I'd buy a dedicated ~1/2HP chiller to use with the buried piping to cool the FT and surrounding ground, but meantime I'll just use ice and my old fridge unit.


I've started feeding only 5mm pellets now, they eat a greater weight of feed compared with feeding them 3mm. I'll bag the remainder of the 3mm pelets up and freeze them.

Great to see, the ice and freezer cooling must be costing you a fortune.. How far away are you from a trout harvest?

Also is your current cooling solution having an effect?

Yay for 5mm! Are they floating? and are the trout still eating well?

They should be taking the 5mm without a problem... I actually switched mine to the 7mm today.... (ran out of 5mm )