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Dry Granule Fertilizer and Urea for Fishless Cycling?

Hello everyone!

I have been reading a lot on Aquaponics and just a few weeks ago finally decided to start my own system and i have some questions.


1. I am wondering if it is 'safe' to use Granule based Urea fertilizer which is 46n (sodium) 0p (phosphorous) 0k (potassium). I found these at my Local Ace Hardware branch. I plan to use this for the ammonia that Urea eventually generates, there was another product called "Ammonium Phosphate" but I read somewhere that this unwise to use in Aquaponics.

2. Another product of the same brand (the brand name escaped me) is a "Complete fertilizer" also granule based and has 14n 14p 14k.. I was wondering if I can use this as my nutrients substitue for my plants while cycling fishless.

3. Another question which is mostly on Fish care is; do Salt prevent "All" of the fish disease such as Ich and fungi? Is it the only safe way to treat fish within a fishtank that delivers water to the growbeds?

Really want to start my system already, but getting a hold of the materials needed was harder than I thought from where I am from.

Many Thanks!


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I know of many people in OZ that will cycle up systems using urea fertilizer (when you say 46n I think you mean nitrogen not sodium)

Drawback with urea is that it will take time to break down into ammonia which is what the bacteria convert to nitrite and then other bacteria convert that into the safer and plant usable nitrate.  Since urea takes time to break down into ammonia, it is easy to over dose your system and actually slow or even stall cycling but it will work.  There is just no way to add it and then be able to know if you added the right amount since it can take a week or more to break down into ammonia.

I would be inclined to caution against using the other fertilizers since it is hard to know the effects of such fertilizers in an aquaponics system and you don't want to risk metals building up that could kill fish later.

Salt, no it probably doesn't prevent "ALL" diseases but it can be used to treat most ich and fungus (most of what people call fish fungus is actually bacterial infections) but no treatment is guaranteed to save all infected fish, how effective it will be will depend on many factors.  Keeping new fish quarantined for a time and perhaps doing a salt dip before putting them into your system can help though.  And as far as safe for aquaponics, I would say yes salt is the only treatment I would use within an Aquaponics system since most other treatments are either unsafe for food fish or food systems or will kill the bio-filter.

Lol, I was never good at chemistry class. Thank you TC! Definitely noting these. 

I noticed in that primer on Aquaponics("Rules of Thumb"  and "Cycling") they mention ammonium chloride as a good source of ammonium ions in fishless cycling.  While this is fine, an equally good source of ammonium and probably much more readily and cheaply available would be ammonium sulfate, the fertilizer.  You just have to look for pure ammonium sulfate, not one of the more balanced fertilizers with the other nutrients too.   I've used this for salt water and african ciclid aquariums as well as my AP tanks.  

They also mentioned human urine, which i've used also.  There is a risk not so much from bacteria (most people's urine is sterile), but from any drugs/supplements/vitamins they take.  They also mention that ammonium isn't readily available from urine for a long time.  I disagree.  Urine has nitrogen in the form of Urea which is just ammonium carbonate, and in solution form, presents ammonium ions immediately.  There should be no need to brew some nasty old urine.  The issue with drugs, etc in the urine is the greatest, since we now hear about things like birth control drugs, antibiotics and many other common drugs now showing up in the lakes downstream of sewage processing.

The issue I've seen with Urea fertilizers is to be careful of something called "Sulfur Coated Urea SCU", where the urea nuggets are coated with molten sulfur, which slowly breaks down in the soil, thus makes the fertilizer slowly available to plants.  In a pond, I don't know what that elemental sulfur would do; greatly increase the acidity eventually, as sulfur is biologically broken down to sulfur trioxide(sulfuric acid).  This is already in sulfate form in the ammonium sulfate.

Having done pee ponics and cycled systems with urine.  I will agree that Hummonia (urine) is a great source of ammonia for cycling a personal home system (if you are taking the drugs then obviously you are not too worried about ingesting them in the first place.)

But I will disagree that the ammonia shows up immediately.  There might be some of the urea content of urine that will convert to ammonia almost immediately but most of it takes a little time to convert.  I've dealt with far too many people who have a pee party and then test the ammonia and upon not seeing any ammonia reading, they proceed with the beer drinking and peeing until the ammonia starts to show up, unfortunately by that time they have added so much into the system that will continue converting from urea to ammonia over the next week or so that the ammonia level winds up off the chart and sometimes even gets high enough to inhibit proper cycling at all.

Please be careful about overdosing with urine or urea into a system.  Dosing more doesn't necessarily help.  It can actually slow cycling down to have too much ammonia.

Keep in mind that urine will vary from person to person and even from pee to pee from the same person.

About a pint per dose was enough for me to cycle up my old big system which was about 600 gallons of fish tank at the time of fishless cycling.  I didn't dose ever day.  I tested to see where things were before dosing  and I did used aged urine so that the ammonia readings would show up after dosing rather than having fly blind.

I have tested fresh urine and the ammonia readings really didn't show up for fresh urine.

Neither urine, or urea... will convert and/or show ammonia immediately...

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