Garden fertilizer as aquarium fertilizer?

[psionicfish]

Sorry if this is a stupid question, and im sure it has been asked before (searched, couldn't find though). Before spending 50$ on a ton of flourish stuff I found a "Tropical Plant" fertilizer mix that seemed pretty potent, rated 20-6-16.

Contents: Nitrogen: 20%, Phosphate:6%, Potash: 16%, Calcium: 1%, Magnesium: .5%, Iron: .1%, Manganese: .05%, Molybdenum: .0005%, and Zinc: .05%.

Almost all of the traces, macros, and micros, are gotten from the exact same compounds as would be found in aquarium plant fertilizer. But at about $5 a pound, this would seem to be a potent, inexpensive, everlasting bottle of aquarium plant fertilizer that would cover most traces/macros/micros in one small dose. Can I use this to at least cover macros or will it kill everything somehow? :huh:

 

[RTR]

Most garden fertilizers use ammonia sources for nitrogen, which will produce algae heaven. The N ratio is off for aquatics as well, for aquatics it is normally about 10:1 rather than the 20:6 (10:3) offered by the garden fert.

 

[psionicfish]

Ok, hypothetically say I use it.

#1 What is the worst that could happen?
#2 Algae out burst (from ammonia) and I have to get a pleco/sae? Wouldn't my bio wheel be able to handle the excess ammonia?
#3 What would happen if I over-fertilize? More algae or death to plants? If death, could I prevent it?
#4 Could I use it in small doses to cover the K/P/N?

I would be grateful if an expert could answer my above questions.
I will get a detailed list of where the traces/macros/micros are derived from next time I go to the store (few hours) if anyone still cares.

 

[Watcher74]

I'm no expert but with that much ammonia being released the worst you will see is:

#1 Death of every fish
#2 Algae bloom from H E L L. It will very likely manifest itself as pea soup so thick you can't see anything. Starving your plants for light and killing them off a little slower than the already dead fish. A pleco couldn't help even if it did survive long enough to get hungry.

If you could safely use normal potting soil people would be using and recommending it. It would be a lot cheaper. But I have yet to read a single person who does recommend it. I've read numerous who specifically tell you not to use it.

 

[psionicfish]

I don't plan to use it (you guys have convinced me), but what if it doesn't contain ammonia, would it be safe? What else would I have to look out for?

 

[Watcher74]

I'm a fan of getting a soil rich in iron(like flourite) and adding fertilizers to the water column. Reasons:

1. If you depend on the soil to put all of the nutrients into the plants, then it will eventually be depleted. You would not be aware of when this would happen until the plants started to die. Then you would have to entirely tear the tank down and start over.

2. With adding ferts to the water column, if you mess up by over/under dosing, then all you have to do is either a large water change or to add more of the needed nutrients.

3. Every tank is different with its own needs. By adding nutrients to the water column you can adjust what you add for your individual tank. There is no one-size-fits-all that would work in every tank. You can easily adjust adding nutrients to the water. Not so with the substrate.