If you use only one fertilizer/macro/micro,let it be iron. According to pro aquarist.


Fish Addict
Dec 10, 2018
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He says he's not tried every form of fertilizer because he finds just liquid iron is enough. That's pretty much what I have come to the conclusion of. Liquid iron aka iron gluconate does wonders with all plants including hydroponics. Ok,potassium also can be VIP. But all the rest?..not essential.


Fish Herder
Aug 8, 2015
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What do fish excreat. nutrients. So if you have enough fish the nutrients from the fish may be enough to get good growth. Add in nutrient in the tap water and your in good shape. If you don't have those 2 things then you are going to need a lot more than iron. There are14 nutrients other than CO2 and light and water to grow . If ANY ONE is missing your plants will not grow and or die. Some people have very soft water with little to no nutrients. And some of those also don't have the space for a large tank.

The main reason iron is so popularisthat each type of iron salt used in fertilizers has its limitations.

Iron Gluconate: Gluconate is a type ofsugar. Bacteria wil consume it quickly. Once the gluconate is gone the iron oxidizes and settles to the bottom of the tank. Iron oxide is not soluble in water and as a result plants cannot use it.

Iron EDTA. Is also widely used. Bacteria will not consume it like gluconate but at a PH 6.5 EDTA separates from iron again resulting in iron oxide.

Iron DTPA Similar to EDTA but it degrades at a PH of about 8.

Iron EDDHA: Stable up to PH of 10 but tints the water red.

So of all of those iron salts with is best for all tanks. None. YOU need to customize the fertilizer to match you water parameters. Or you add a lot more than necessary to get good results . But you will only get good results if iron deficiency is your problem.

And the problems not limited to iron. If your water has a high KH and your fertilizer has Manganese sulfate the will turn into manganese oxide which is not soluble and and settles to the bottom of the tank.

Also one of the 14 nutrients plant need is calcium. But if you look at most fertilizer on the market none have it why, it reacts with posphate which destroys the fertilizer. So most fertilizer don't have any which shouldn't be a problem since often tap water has enough. But if you live a place like bend oregon which has a GH of less than one degree. most fertilizers will not work.

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