Backyard Aquaponics
A place to discuss aquaponics

You could, but I don't think it would speed the process much... and if you're gunna pee in it.... why bother with the urea at all ...

Pick this to bits for me.

250g of urea in 20L of water, with a full bladder to kick things off.
Urea is 46% N. 115g of N in said drum. Cover and set aside

1 ppm = 1g N to 1000L of water.

20L divided by 115 to get 174mL of solution with 1g of N to add to 1000L of fishtank.

Assumptions:
-The enzymes mentioned continue converting the urea after they have finished with the urine, and that the 2xNH2 parts of urea simply break down (pressumably with water) to form NH3.
-That N and NH3 are near enough the same size to treat them the same in the maths.

It sounded like a lot of pee. I though a handfull of urea would bulk it up some.


No thoughts on Ammonium Sulphate??

It doesn't take much pee to cycle a system really. (well if you are talking about a huge swimming pool it might but I cycled my 600 gallon large system using less than a pee a day.)

I cycled a barrel ponics system using doses of 200 ml of aged urine and I think I was using too much. I probably should have been dosing that system with about 50-100 ml of aged pee.

I expect that for a 1000 liter system, it could be easily cycled with doses of between 200 and 500 ml of aged urine. Probably no need to beef it up.

However, I'd be interested to hear what happens if you put some urea in a container of water and seal it up for a couple weeks. Does it convert? This would be interesting to know. Perhaps some one who has some urea fertilizer on hand could run a little test.
One container just water and urea
another container with water urea and a pee
Perhaps another container with just pee
Leave all containers for 2-4 weeks and then mix a measure from each container into a measured amount of water and then test the ammonia levels. Perhaps even do the ammonia level tests each week after starting the experiment?

Sorry, I'll not be running this experiment as I don't have any urea fertilizer to use and I'm not gonna buy any since I would rather just use the free Hummonia if I need it.

I was going to do it. I have some open bags I think, so I don't have to break into a new pallet. I wish I could find more info on easy-N (liquid fert). I'll use your parameters. Two 20L drums, one with 250g of Urea, the other with the same Urea and 100mL of pee. I'll use a smaller (500mL) container for the straight pee or I'll have to get the neighbors involved. I'll have to dilute the sample to test I imagine, unless there is a test kit that can go higher than about 8 ppm. I think 250g of urea in 20L of water should convert to 6 ppt of NH3, not counting the pee.

Yes I definitely expect you to need to dilute to measure things.

When you say 'aged', how long would you guess is enough? It is 38 deg C here today.

One for the scientists. I tried to do a NH3 test on day old urine. Didn't change colour so it either has no NH3 or heaps. What will the test show if the sample is over 8ppm, and what kind of procedure would you use to do a dilute test, given you don't know if the first test is out by a factor of 1000 or 10?

I have read the analysis of urine is roughly 12/1/? NPK. That can't be right!

Why can't it be right?

I would age the urine for at least a week before expecting much of the urea to be converted to ammonia. At least a week to ten days is what mine usually took to get to a pH over 9. Two weeks seemed a fairly safe time to wait for killing off pathogens.

I would expect the API test kit to go very dark green with a huge amount of ammonia but I haven't tried testing undiluted samples.

Remember that I was able to get a barrel ponics system (aprox 40-50 gallons) up to a 1-2 ppm ammonia reading by adding only 200 ml of aged urine.

I questioned the analysis because urine is said to be 95% water, and even if the whole remaining 5% were to be urea, and urea is 46% N, then that should add up to about 2.5% N per volume in wee. But I am overlooking any other source of N.
I added about 20g of Am Sulphate to my 2500L (only part fill for the moment. Is that a bad idea?) and the water tested at 1ppm. From here I should keep testing (once a day?) my NH3 until it drops, then add the same again? By then I should have my full test kit so I can test for NO2 and NO3. I can do this for a week or so until the urine ages. If I do a NH3 test on the urine and it goes dark green, I can consider it aged?

can you test pH? I would say when the urine gets to a pH of around 9, you can probably call it aged enough.

I've got my pee ageing at the moment, can I throw in some worms and castings before adding the 'humonia'.

Also when would you add plants before or after it's cycled?

Put your plants in now...

Thanks, I'll have do duck down to Bunnings and see what they have.

Worms and some castings can be added now (but if things are really clean, there might not be anything for them to eat.)

When buying plants, best to rinse the dirt out of the roots when planting.

Thanks for starting the thread, TCL. Nice to have it in one place.

Good calcs on the urea, Dexter. I've figured 1.7g per 1000 liters should give 1ppm, so diluting to make a standard solution is a good idea (essentially synthetic pee for those who are squeamish or have large systems or health problems). If you diluted 17g in a liter you could add 100ml per 1000liters to get 1ppm: easy numbers, fewer mistakes. For those of us stuck with "standard units" one could make a solution of 22g in a liter and 10 fluid oz in 1000gal would give 1ppm...I think.

I've read that the bacteria grow fastest at 5ppm. Is there any reason not to start with that since there are no fish?