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I was wondering if anyone knew what the ratio would be to use fish waste(poop) and water for watering the plants outside of my aquaponic system? Also, what would the shelf life be?


Thanks, Scott

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Scott if you are using the water out of your system then you can use it straight. I have pumped ponds dry and the bottom was covered with fish poo and other debri. I have mixed this as rich as a 1/4 of a 5 gal bucket with poo and the rest with water and watered my clients lawns, gardens, and ornamentals, with no problems. So I guess the ratio would be 1 part poo to 4 water for an unscientific trial. Start light and experiment .
I would assume, as David said, that you can use it straight; the same bacteria that convert NH3 (ammonia) into Nitrate in a aquaponic system live in soil, so actually after you put manure, or chicken shit as some call it, as a side dress or starting fertilizer, that you should put fish tank water on it. Also this could work with compost-- these are assumptions that I'm going to experiment with. I think David's advice might be more helpful though: I started gardening a year ago.
If I bottled it to store it..Do either of you have a idea of shelf life?

Hi Scott,

You can't bottle/store it for any period as it will be overcome with anaerobic bacteria which smells lousy and when used on soil based plants will harm them by the toxins they produce. However, you can dry it and use it to fertilize your plants when needed.

Hi Harold,


So what about a day or so? How do you dry it?



Hi Scott,

A day may be too long as these bacteria multiply very quickly. You can pass it through a sieve ( fine mesh ), spread it in direct sunlight, or by artificial drying (oven ).

Hi Harold,


Then after drying it, do you just add it to water for fertilizer?



Is there anything you can add to give it a shelf life?

Hi Scott,

Adding water to the dried waste will allow the nutrient to become available to the plant roots. Since these bacteria multiply in the absence of oxygen a constant adequate oxygen supply will extend shelf life and over a period of time releases all its nutrients to the stored water . You can, if you wish, also freeze it. 

I would say simply spread the poo directly around the plants as a side dressing fertilizer.  I wouldn't leave it sealed up in anything, heck even letting the wet stuff sit in a bucket will probably produce a stink that will gag you.  If you must leave it sit around for a time before using it, leave an air stone bubbling in it.
And if you leave it sealed up it will produce methane and blow up (Not like explode but will break the container). Don't believe me? Fill up a milk gallon and leave it in the sun for a few days. Big...stinky...mess
I think this method of removing fish waste from AP systems has its use. I ran almost double fish ratios early on in my AP and separated 50%waste from the system for dirt plants. So this applies to a person who wanted a design to harvest more fish from their AP than the standard ratios allow. Waste contain valuable nutrient and it won't go to "waste" this way.Running this way ensures more than adequate nutrient will be available for the high density of plants in the AP system.

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