Backyard Aquaponics
A place to discuss aquaponics

Not to discredit any of the ideas that anyone has shared... but I think we need to stop and ask ourselves is PLJ actually asking for help or are we trying to fix something that he never said was a problem? I mean now we're talking about redesigning his entire tank? Do you think that's really likely or feasible? Have you taken the time to actually read all 51 pages of this thread before making suggestions about redesigning the tank? I don't see how redesigning his tank has anything to do with the problem he stated that his tank is getting too warm... I think there were a lot of great ideas on how to keep the tank cooler but I think we've probably came to a point where we're soliciting ideas that aren't asked for or aren't solving any problem that he has just because we think he has a problem even though he hasn't really said it's a problem...

Rob, I believe for any given lat/long there is an identified or at least calculable changeover point at which the insolation (incoming solar radiation) which is absorbed by a surface reaches a level where it surpasses the heat lost through radiation from that surface, thus resulting in a net gain for the day. There would be a corresponding changeover point for daily net loss when the seasons change.

This is mostly due to the length of the day and the position of the sun in the sky and no doubt will vary according to the nature of the surface in question, and other factors like altitude and of course shadecloth. My point is that you may be able to identify the actual dates when it would be worth your while covering, and later uncovering, your media beds.

I don't think you really need to set a date, as the daily and weekly weather variations will make the date vary from year to year (unless you happened to live somewhere with extremely consistent sunny weather). I cover my GB media when the water is clearly on a warming trend in Spring, overcoming the daily to weekly variations, and have done this for a few years now, as it works to extend the time I can keep the trout in my small system. In the big system I also cover the media in the warmer months, but with buried GBs, the overall warming of the ground is a significant factor in the water temps, so I've been running a chiller to keep the water cool enough.

I understand that it's not a question that was asked. And I have rethought the idea, I still think it would be the best way to set the bottom of the tank but I have a mind that runs.

This is what I would do with the tank. May be a lot of $$$ and work but it would be a special system.

(I find that designing stuff helps take my mind off of the agony I feel 24/7. You have to do something with your time when you are awake 23hrs a day.)


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I've painted my rafts with A1 Pond Paint. Perfectly safe for fish and my taste is 3yrs old. No perishing. I went with light grey.

I was silly and snapped the corner off when I took it out to clean but sun has been fine.

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I think he already has growbeds with all the associated benefits, and filters too.

The weak point in this design looks to me to be the exterior pump and plumbing fed by the drain from the bottom of the tank; that's a lot of water pressure and a failure of fittings etc could drain the tank!

I seem to recall from previous reads of this thread that PLJ has SLO from tank thereby removing solids, with fail-safe design to mitigate against draining the whole tank by accident.

Sure the decking over the tank could be really aesthetically pleasing, but obviously that's an absolute bunch of money and work.

please make of video of you scooping fish from the tank mate, should be hilarious viewing.

When I put a barrier in my pond it made it so much easier to harvest the fish. I stand behind the barrier with a net near the end, then put another net on the far side (where all the fish are) the fish race around the end of the barrier straight into the net.

I drained the tank from Wednesday night through to Friday morning last week and caught all of the fish, bar one, on Friday morning. I had to go as low as 150mm deep to finally get them but one rainbow managed to elude me so many times that I gave up on her, leaving her to her fate. I kept two small browns in a holding tank with no real plan for them but all others were processed and sold at my farmers market stall on Saturday morning. Regrettably I picked a period when the weather was very hot to have no water flowing through my growbeds. I've been busy hand-watering to maintain the valuable plant life contained therein but I will have losses. The tank won't be back up to minimum draining/pumping volume until Tuesday.

Slowboat, assuming I grow trout again next year, I have between now and next November to devise a better way of catching the trout at the time when they aren't actively feeding. Before that time is alright because I can generally scoop several at a time at the surface as they feed, or alternatively haul them out on hook and line with my trusty tiny Ugly Stik. I may have to have a closer look at your set-up.

An idea came to me recently about installing decking and grow beds over the top of the tank; like yours, Slowboat. I'm just toying with the concept for now but I'll keep you posted.

Ronburgendy, I appreciate the time and effort that you have invested in designing a possible rebuild of my system. You may have given answers to questions as yet unasked but I don't mind at all. I'm happy to admit that my system was never actually designed as an entity but just evolved in time with little bits of actual design added here and there. Your suggestions could well plant the seeds for later improvements or rebuilds so I thank you in advance for them.

What's the story with only one hour's sleep per night?

The main areas for improvement that I've identified, able to be achieved without a total rebuild, are as follows:

1. a methodology for catching the fish, in a non-injurious way, at any time;

2. complete protection of FT water from direct sunlight, either by use of a solid or a shadecloth overhead structure;

3. greater rate of turnover of the volume of the tank, since currently the volume turns over in around 7-9 hours. (Possibly only necessary if I want to stock 600? or more fish.) Not necessary now because I grew out nearly all of the 538 trout and 3 silver perch that I started with this trout season.

This is the last trout to be pulled from my tank for the year. Ironically, it was a brown.
Regrettably, although I knew it was in there I couldn't catch it and had to wait until it inevitably died a couple of days after the final harvest.

hows the bottom of the tank look? your massive SLO network appear to be working well still?

I'm not sure if my method for draining solids from the bottom of my tank is correctly termed a SLO since it exits via the tank outlet under head pressure rather than over the wall via siphon action. Regardless, it's in good working order. I detached each component and gave it a quick clean. I also increased the height of the centre pole by approx 30cm in order to increase the distance between the water surface and the bird netting and shade-cloth.
Note the algal build-up which has occurred in around four days.

Once the original mature water was mostly drained and a proportion of new underground water pumped in, the water was much more supportive of algae growth. The reason - old mature water retains an algal growth retardant that is created by dying algae in an earlier bloom. New water, with retardant totally absent, very quickly grows algae.

PLJ, what temperature is your underground water, and what sort of flow do you get from the bore?



You caught ~500 fish, gutted and cleaned them all on Friday and sold them all on Saturday??? Thats a mighty huge effort!

Can I hire you for a day to help with the ~300 I want to take from my FT soon? ...I'm leaving ~100 to carry over for next year, to save buying new fingerlings in Feb.

It must be a huge farmers market, we can only sell ours as "pet food" because the NSW regulations make it impossible for small players to sell for human consumption (the fees are more than our potential sales), but would only sell 2 or 3 per week at the growers market on average.

Guna, you haven't been keeping up with the program. I've been progressively harvesting my trout since September and, on 3 Dec, said:
As it turned out, I'd miscounted somewhere along the way because there were only 47 fish left in the tank when I drained it, including two silver perch. I took 39 rainbows, three browns and the two silver perch to the farmers market and sold them all. (I've kept two small browns in a holding tank with no plan for them.)
The fees are an issue of concern here in WA, as well, to the extent that I've had discussions with the local MP on the matter. I'd be happy to discuss this issue offline.

Ahh, thanks. I didn't scroll back far enough, 13 days is a long time in forum land

I'm thinking of visiting the local MP myself, to see if something like the Qld laws can be introduced here, I'll send you a PM