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Is it possible to run an aquaponics system temporarily (say 1 month) with out fish, perhaps using ammonia and liquid seaweed as inputs?

I built an outdoor aquaponics set up for my girlfriend's parents at their summer house in Rhode Island (8 sqft growbed, ~50 gallon tank). I started the cycling process yesterday (May 19th). The plan was that her parents would arrive on June 1, when system would be cycled and we could add fish. However, they just informed me that they won't arrive until mid-June, which is about a month away. I can't put the fish in until they arrive (no one there to feed them) but I want to start growing veggies because we've got such a short season (plus I bought seedlings).

I read on the 'Aquaponic Rules of Thumb' page that one can plant the seedlings as soon as you start cycling. The question is, can I get them growing for a month or so without fish? I've got lots of liquid ammonia and a couple jugs of Maxicrop/liquid seaweed. Can I plant the seedlings now and then add regular doses of ammonia and Maxicrop to keep them growing until the fish arrive in mid-June? This would seem to deliver plenty of Nitrate and Potassium, but I'm wondering if there are other trace minerals from fish/fish food that would be missing.


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If you can be there to dose with ammonia every couple days, why can't you just feed the fish yourself?  Fish don't have to be fed daily and if you can be around to dose and test a system often enough to cycle it up and tend the plants?  Why not feed the fish?

That said, yes a system can be run fishless indefinitely but you are right in that pure ammonia and maxicrop may not be quite enough to cover everything the plants need.  They will also want phosphorus which is usually supplied amply by fish food/poo or even by hummonia but I'm not sure what to recommend to provide phosphorus to a system being run on just pure ammonia and maxicrop.  Perhaps some one else who has actually tested it for a while can chime in.  Perhaps some bonemeal would work if you feel comfortable about using it.

Thanks TC. Your suggestion would work, but I was planning to be there only once a week at best (3hr round trip), so I'm not following the ideal cycling plan, and that's probably a bit too long to go without feeding fish. I recognize the ammonia/maxicrop route is not optimal, but I'm trying to figure out next steps since this curveball of scheduling was thrown my way. 

I think your suggestion of hummonia could work, provided that I keep that a covert detail from her parents, but I'm also open to bonemeal.  Of course, perhaps my best bet is to just suck it up and make a couple trips down there per week for a while. It would be good to monitor the progress of the system better and I could probably introduce the fish.

That said, I would still appreciate opinions of others who've tried this to see what you've used for your phosphorus.


Pee ponics (hummonia) is best done for your own system and I wouldn't recommend it be done to some one else without full disclosure.

I know that a number of Aussies run their systems for months on end (if I recall correctly, which I believe I do) fishlessly using a product called "Charlie Carp" (it appears to be some kind of fish emulsion made from ground up carp, but you can Google it I'm sure)...

For fishless systems in terms of phosphorous, personally I've used aged crushed up and ground to a powder, bones from pigs, but you can just buy the bonemeal. It's pretty damn slow acting so don't expect results (bio-availability) right quick. For that I have used rock of phosphate. You can use both but be careful not to over do it (easy to do) as it could apparently cause a whammy of an algae bloom...

Personally I'd go with hummonia, a bit of Maxi Crop (for trace elements) and a couple handfuls of worm castings brewing in a sock next to an air stone. The castings I had were tested out at the following:

N-1.41%  P2O5-1.73%  K2O-1.58% Ca-2.80%  Mg1.85%  pH-8.42

But I imagine these (your) exact figures may be a bit different depending on a host of things, (worms diet, type of worms used maybe even etc...) but I'd expect them to be somewhere in that ballpark. You can probably use those numbers as a ballpark/starting point...Hummonia is also 'chockful' of essential elements other that the nitrates it offers...Somewhere in the range of 11-1-2 to 15-1-2 (I've not personally tested mine, these figures are from Scientific America and wiki and also are probably dependent on a host of factors)...

As far as the, non-disclosure goes...hummonia could offer some harmless Mall Rats "Chocolate Covered Pretzel" type satisfaction, depending on how well you get along with her folks 

I have tested out Gro-tone 2-2-2 Fish emulsion fertilizer in a system and it seemed to work ok.


Interestingly enough, it smells like Mint.

  I didn't test super long term with it but I didn't kill any fish with it over the 2 months the fish were in the system and I did use perhaps two bottles of the stuff on a system that was only about 200 gallons of fish tank and at one point I dumped enough in to actually spike the ammonia and nitrite a bit (fish were in the system while I was dosing with it, I don't recommend this though) so I know it is at least not immediately or acutely toxic to koi, goldfish, bluegill or channel catfish.

Thanks very much to you both, this was very helpful!

I fired up my new greenhouse with the the good old pee-ponics method.  The system has been running for about two months now....just introduced a few fish to the tank over the weekend. 

Thanks Rob. Any ratio you used relative the to the tank size? Or did you just monitor the ammonia and nitrate levels and adjust as needed?

Rob Torcellini said:

I fired up my new greenhouse with the the good old pee-ponics method.  The system has been running for about two months now....just introduced a few fish to the tank over the weekend. 

just monitored the ammonia levels....I"m not very scientific with my system. 

And hummonia (pee ponics) is going to vary since not everyone pees the same mix or strength.

When I cycled up my very first systems back in 2007/2008 I figured a pint a day of aged hummonia would be enough to cycle most any media system with a fish tank up to at least 600 gallons and it would probably do up to 1000 gallons.

The act or process of adding ammonia or urea to cycle a system is an artificial means to jump start a load out for faster more humane results. The system will actually establish itself with only the pump running using atmosphere and oxygenated water.  It just takes forever and a day...maybe two.


If you are going to do peeponics I would recommend that you bottle it for at least 8 days before adding it to the system. Straight "unaged" urine is not as effective as pure ammonia but does work.  


Whatever method you choose you won't experience explosive growth results until the system cycles up to 15-20ppm on your nitrate nutes.  Low nutrient leafy plants will work better in a system that hasn't completely cycled but you still have to maintain your pH below 7.4 which doesn't really start to happen until the nitrites are maxing out.  Just don't expect rapid plant growth before this happens because most plants will be on nutrient lockout with a high pH.


Make sure you send pictures over so we can see what you figured out :0) 

Thanks to everyone for your earlier advice. Their is bad news and good news. The good news is that the system is growing very well (see pic below). We ended up using mostly ammonia and liquid seaweed (with iron) as inputs, although I put about 5 cups hummonia in over a month period (so about 1 cup per week).

The trouble is now with dead fish: my girlfriend's parents are taking over operation and water testing. According to their most recent tests, the pH is about 7.5, ammonia 0ppm, and nitrate 5ppm (that plants have used up most of nitrate, it was 80ppm a few weeks ago). All the parameters appear to be that of healthy water, but her parents have now introduced fish twice, with almost all of them dying shortly thereafter. Unfortunately, the air stone was not installed, but the siphon dumps water back in for 5 minutes every 15 minutes, which churns the water and should give a fair bit of oxygen into system.

Try #1:  But when they introduced about 40 inch feeder goldfish on Saturday, almost all died on impact. To be fair, they did keep the goldfish in a bag overnight, so the fish were probably stressed for oxygen.

Try #2: They got 25 more feeder fish, brought them home relatively quickly, and put the bag in the water for about 20 minutes to let temps adjust, then opened it up. Again, most died about on impact. I wish I had more detail about how fast the fish died and how long it took them to get the fish home, but i don't have that detail yet.

System is a 50 gallon fish tank with an 8 sqft growbed that is 1 ft deep. Has a bell siphon that cycles every 15 minutes. Media is expanded shale. To control pH i was using a phosphoric acid pH down. Any thoughts?

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