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View Full Version : Osmocote as aquarium fert.?



Capt. Oblivious
02-26-2011, 07:06 PM
On some websites I have heard that there are people that use osmocote fertilizer in their aquariums. Does anyone use this/tried it? If so is it safe for the fish in the tank? Anyone with knowledge on this please reply.

MCools
02-26-2011, 08:04 PM
I would not try it. That's meant for houseplants and gardens and is not made with aquatic life in mind.

There are plenty of aquarium ferts out there that won't hurt your fish, and they usually don't cost too much. I think I would play it safe rather than end up sorry.

gm72
02-26-2011, 08:12 PM
A lot of terrestrial fertilizers contain ingredients not conducive to the aquatic environment. I wouldn't recommend it.

Goes to 11!
02-26-2011, 08:28 PM
Here's what's in it, You decide.

Osmocote [From here (http://www.scottsaustralia.com.au/images/MSDS/Osmocote_Total_All_Purpose__1052_.pdf)]

Section 3 - COMPOSITION/INFORMATION ON INGREDIENTS

Proportion % w/w
Active ingredients:

Ammonium nitrate
6484-52-2
20-35%

Mon-ammonium phosphate
7722-76-1
<5%

Urea
57-13-6
10-15%

Magnesium sulphate
7487-88-9
<1%

Magnesium oxide
1309-48-4
<1%

Potassium nitrate
7757-79-1
20-35%

Boric acid
10043-35-3
<1%

Iron sulphate
7720-78-7
<1%

Copper, iron, managanese and zinc EDTA
14025-15-1, 15708-41-5, 15375-84-5, 14025-21-9
<1%

Sodium molybdate
7631-95-0
<1%

Non-ionic surfactants
-
2-5%

Alkyd resin coating
-
2-5%

dbosman
02-26-2011, 10:57 PM
Osmocote and Osmocote plus are a simple, inexpensive fertilizers when compared to other labeled "aquatic fertilizers". The source of nitrogen in it can - not will - cause some issues if it is in the water column. Kept under the substrate where it can time release, it's fine.
So fine it has been used in planted tanks for more than twenty years that I know of. Occasionally, after moving plants around, you have to push the little plastic spheres back under your substrate. It is not a suitable fertilizer in tanks with fish that move substrate around.

The usual complaint about Osmocote is the cost, if you aren't a gardener. At $10. - $20. per container, a tank enthusiast is buying several lifetime supplies. That is still far less expensive than most name brand root tabs.

A less expensive alternative for substrate fertilizer is Jobe's Spikes for Palms and Ferns. I get mine at the hardware store. Thirty for $2.29. Break each spike into three pieces and shove under the substrate a couple of inches away from the plant. Or on a grid of 3" x 3" or 4" x 4" depending on who you believe.