Backyard Aquaponics
A place to discuss aquaponics

Just a report on my major fish kill, and the progress on the remaining tough little survivors.......
I have now got the PH of my 200ltr F/G fish tank back to the middle and the water temp is a steady 23 deg - Today a made up a filter from a large plastic plant pot which is 300mm high and about 300mm dia, put it into the pond with about 100mm very course gravel in the bottom, then about 150 to 200mm of F/G insulation pink bats then some fine grushed blue metal on top.....

Then set up a 500 gph Rule bilge pump to pump into the top of it from the bottom of the 200 ltr tank and allow the water to go down through the plant pot and the excess water just spills over the side assisting with aeration.
It's only been running for about 4 hours and the water is sparkling already - amazing stuff....
The remaining fish that I haven't managed to kill are having a good time and are looking well... I hope that things are getting better for the poor little mongrels now.
Murray

Good to hear Murray. But don't forget that although the new filter is making the water clear, it's not removing ammonia buildup from the system, you should give it a 30-50% water change out every couple of weeks of so, just for a month or two, or untill you get your new system built.... On that subject, did you say that the fish tank is going to be roughly the same size as the growbeds but deeper??

Ok earthbound,
Is that because those trickey little bacterium's that gobble up the fish by-product, will take some time to form in the home made filter ?

And yes, I will be making a couple of different size tanks, but the first one will be just about the same size as the grow bed but 750mm deep which will be around 1350 ltrs useable capacity, that will be for one of the Forum members

I am also about to start on one which will be same length and width but 1000mm deep giving around 1900 to 2000 ltrs

Murray

Yep....... And then once the bacteria become established, you'll end up with nitrates and/or nitrites building up in your system instead of ammonia.. Not to worry though, fish can handle higher levels of nitrates than they can ammonia, just have to get some plants into it at some time to extract it....

Joel,

To save worrying about heating, I may go with silver Perch fingerlings or fry at the school farm. U have a contact no. for your supplier?

My tanks at school are not ready yet, but the students are eager for us to get something growing bless 'em!

Does he deliver? .. (I only need 40 or so?)

Cheers

Johnnie

Hey Johnnie,

Yeah, go for the silver perch, in the climate we have here in Perth, the more I use the silver perch, the more convinced I am of them being one of the best fish for aquaponic systems, in this climate we have.. And only because we can't get large quantities of Murray Cod fingerling to try properly..

The silver perch I got were from 'Arcadia aquaculture' in Badgingarra, I think his name might have been Brad, maybe.. Anyway he was very helpfull for me, he does trips down to Perth on a fairly regular basis delivering fish to aquarium shops etc, he is at 9652 6060. Mention that the crazy aquaponic guy in South lake put you onto him, the more he hears about aquaponics, and the more people buy from him for aquaponic systems, the more likely we are to get better prices and service...

Joel

Hi, can anyone give me a tip or two on keeping the ph of the water to about 7.0 ....... As I am exchanging about 1/3 of the tank twice a week with rainwater which is way beyond 7.6 alkaline, I am using Sodium Biphosphate to bring it back down to neutral, and try to keep it roughly there.

Is there any other way of doing it ?

Does anyone who has kept Silver or Jade Perch know how tolerant these species are to Ph swings long term.

Murray

Thats a lot of water changes Murray... Luckily you won't have to keep that up for too long, I know what it's like in the early stages, I have stocked my new tank for the new system with about 30 small goldfish and in the last 2 weeks since I stocked it, it's now turned very green..... But thats cool, I know that the goldfish will be able to handle it while things are peaking and fluctuating, and it means that bacteria is building up in the tank. By the time I've finished setting up the growbeds and have everything pumping, the system will be well primed all ready for the good fish to go into it...

Sorry, getting away from your question.. I'm not sure about other methods of lowering pH, I normally have the opposite problem, if any. Take solice in the fact that your system will be a lot more stable once things settle down and bacteria builds up, then you won't need to be makiung so many water change....

I have had my silver perch under some extreme conditions with very low pH and they have survived very well...

Murray,

I've also had silver perch at low ph 6.2 for extended periods with out damage. I assume they would be as tolerant of high PH's

The main thing to remember is that that its SWINGS that really stress the fish out. whatever you do, don't try and bring the ph from 8.0 down to 7.0 in one hit. Ph is a log. scale. so even 0.1 is a big step. try and adjust it .2 or.3 a day for the least stress to the fish.

Like joel says things will stabilise over time and then the ph should slowly drift DOWNWARDS. This is normal due to the biological action of the bacteria. I've found that crushed sea shells do wonders at keeping the water buffered. I think Joel found the same.

Just found this for you:
"Silver perch are able to tolerate pH of between 6 and 10, with the desired range between 6.5 and 9."
http://www2.dpi.qld.gov.au/fishweb/2703.html

So don't stress



Steve

Thanks Steve, Earthbound,
Perhaps I shouldn't stress so much over the poor little mongrels, they are really looking well at the moment, I even thing they are getting a little bigger (wishful thinking perhaps)
I will keep the water top-ups going until I get the big tank finished and have it running well. I may even do what you are doing there Earthbound, get some of those feeder gold fish and put in the big tank to get it all going before transfurring the Jade Perch.
Murray

They're one tough fish hey Steve........

Yeh, silver perch are my fave

Joel, what temps is your silver perch tank at ? could you take a temp for me in the early morning ie before 9am

Thanks

Steve

My Jade Perch are doing just fine, last night we had a frost here at North Maclean and the air temp inside my shed dropped to 4 deg C
The 200 ltr fish tank water temp was at 23 deg at sunset last night and at 7 am this morning had dropped to 17 deg. I am running a 300 watt 240 volt electric heater in the fish tank which is set to 24 deg.
Just now at 5:30 pm the temp in the tank had come back up to 22 deg during the day.
I thought some of you may be interested in that.

My new F/g fish tank will have 25mm of marine grade polyurethane foam skin all around it and I will make up a good lid for it. It is obvious that it is imperative if fish are to be kept growing well during winter.

Depending on what happens tonight I might go out tomorrow and get another 300 watt aquarium heater. I would like to be able to keep the water temp in that ideal range. It will be much harder to achieve when I have the grow beds hooked up. These 300 watt heaters will be a bit useless in a 2000 ltr fish tank, would possibly need a dozen of them !!!!

Has anyone come up with any ideas to keep the temps right in bigger tanks? Veggie Boy was toying around with some solar ideas --- any progress Veggie Boy ???

Murray
murray@boatshop.com.au
www.boatshop.com.au

Murray,

Here's a couple of suggestions for keeping your tank at a useful temperature:

1. Sun-facing greenhouse - this is a lean-to shaped greenhouse that attaches to the northern face of your shed (assuming you can access it). It takes advantage of the winter sun. You could place your fish tank and grow beds in it or just the grow beds.

The Sun-facing greenhouse works most efficiently when it is attached to a solid masonry (stone, brick or cement) wall. The wall heat up during the day and radiates the heat back out into the greenhouse at night. As it is, you'll get something of this effect because of the mass of water and gravel (or both) in your tank and grow beds.

2. Metal Halide/High Pressure Sodium Lights - put one of your grow beds inside the shed with your fish tank and put a MH/HPS grow light over the bed....and then look out. No more problems with daylength, ambient temperature or with cold fish tanks. The design of your lovely tanks lends itself to cladding them in a box structure into which you could discharge the waste heat from the metal halide lights. In effect, your tank would be surrounded by warm air at the same time that your plants would be getting light and warmth.

You mentioned that you were already using a 300 watt heater - grow lights start at about 400 watts and you'd be getting both fish and plants for the money. You could set up the growing cycle on your plants so that it happens at night (when it's coldest) and let them sleep during the day.

I'd probably recommend a 600 watt light on a traveller for a grow bed the size of yours. Get the formula right and you'll keep the fish warm and you'll be carting the vegetables off in a truck. The last time I checked, a 600 watt grow light costs about $12.00 a month to run (and you're already spending half of that on your 300 watt heater). Your fish will grow much faster if you can maintain the optimum temperature. Do the sums!

If you're interested in incorporating a grow room into your set up, I suggest you read "Integral Hydroponics" by G. Low.