Backyard Aquaponics
A place to discuss aquaponics

Hi All
As a science teacher just arriving at a new school (7 weeks ago now) I was given the task of doing something with the year 10's to motivate them in science while still learning lots. I had wanted to try aquaponics so this was the chance. I am very pleased with the way my class has grabbed the idea. We have been getting the stuff together while learning some chem and doing some biol (including a fish dissection).

Our system is an old 250L fridge which had all the compressor etc removed. We have patched and sealed it and yeah, no leaks. This will gravity feed into 2 growbeds each being half an old 220L blue barrel (once used for ginger beer). We drilled a hole in each and now have a self siphoning system. They empty into an old fish tank (sump) with a submersible pond pump in it to pump back to the fridge. A CHOP system.

I hope the system is in reasonable proportions.

The system will be filled tomorrow and we will fishless cycle by adding ammonia and watching. We only have access to town water so I may need to help aerate it as I will not be adding anything to treat the water.

We have dip sticks for nitrite and nitrate, pH and conductivity meters and a dissolved oxygen meter and trusty old thermometer. For ammonia I might just get the kids to do titrations as I have access to that stuff and don't have any test strips for it.

I am a bit concerned about the time for cycling so may cheat and add some water from my home pond. I am also concerned about the number of fish to put in it. I would like Jade perch but I think the system is too small to bother a supplier so goldfish may have to do. Not sure how many I need to make enough ammonia for the plants (probably lettuce and tomatoes). Any suggestion of perch / goldfish numbers (fingerling size).

We have taken a lot of photos and I will post some when I go through them.

I wouldn't use test strips for nitrate, nitrate or ammonia. Test strips are notoriously unreliable. Unless of course I'm confused and dipsticks are something else entirely. Test kits are cheap ~$50 for all tests including pH.

Your ratios seem good.

Most suppliers will sell you the 15 - 25 fish you will need so I would bother them as goldfish are only nice to look at an you can see 'em all that well in the fridge.

Also I advise you get some air in the system. It will assist in offgassing chlorine and also keep the ft clean and tidy. It will Aldo save your proverbial in case someone screws up.

Hi All
System has been cycling for ages. Ammonia is always low but nitrites and nitrates are through the roof. Did fishless cycling adding ammonia every couple of days to get system going then left it to do its job. I have planted tomato seedlings to help reduce nitrate (which it is) but the nitrite level is not dropping. Its way to high to add fish.
I was planning on a 50 percent water change (with neutralising) to see if it will speed up the process and do this daily until the level drops (its about 10 currently). Is this the best I can do to lower them? I need the fish in ASAP.

Photos later today - when i finish marking

looking forwad to seeing pics of the fridge

No more ammonia (you'll just produce more nitrites)... let your nitrites drop by themselves... no water change.... no fish.. just yet... patience...

Oh... and plant what you like...

And if you have access to a cycled fish tank, a few ml of gunk squeezed from the filter will really boost cycling.... We really need some quantitative information on that, but it will help....

Any numbers on nitrite rise and fall trends to date? Graphs are good!