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When and what to fert a 275l planted discus tank with?


19 Oct 2008
Things are coming along with equipping of the 275l discus tank.

I should point out that this is an established tank that's been running for 18 months, but I had to strip out all the plants, decoration and substrate as I acquired leeches from somewhere. Luckily, having spent 3 months as a bare bottomed tank, I have not seen sight of a slimy critter for 7 weeks.

Anyway, the new substrate is now in, and I have 2 - 3 inches of carib-sea eco-complete in the tank.

What I want to ask is this: As I replant the tank (pretty heavily) with an FE CO2 system, when should I start dosing the water with ferts? Presumably with new eco-complete, I don't need to dose for a few weeks or months?

How long would people recommend before dosing, and what product would people recommend? I keep reading multiple threads involving TPN+ and Easycarbo and EI and I can't decide what might be the best way to go!

Thanks in advance for any info people can provide / suggest.


Expert/Global Moderator
11 Jul 2007
Chicago, USA
Well, here's a fanatics point of view: My personal waiting period is 250 nanoseconds after the water level reaches the top of the tank. I mean, think about it, what are we waiting for? Are we waiting for the plants to deplete their nutrient reserves so that they starve and become weak? The transition from emmersed air breathing leaves to submerged water breathing leaves is an expensive one in terms of nutrient consumption, so I see no point in withholding nutrition. As far as I can tell, high nutrient concentrations enables plants to grow more robustly. Many argue that the dosing levels should be low in the beginning to prevent algae or to lower the severity of the algae attacks, but what few consider is that the LIGHTING level should be lowered for the first months. High lighting commands the plants to grow but if nutrients are not available to support that growth demand the plants can fail and algae induced.

In the tropical rain forest the onset of the rainy season causes flooding of the plains, and this flooding also results in turbidity, as all the leaves, soil and leached organic matter on the forest floor mixes with the rain water. This turbidity, plus the raincloud cover curtails the light falling on newly submerged plants and reduces their growth demand. As the water level slowly rises the turbidity is reduced (and so is the nutrient concentration level) so this actually gives the plants a chance to adapt to a submersed environment while not placing huge growth demands at a time when they would otherwise be most vulnerable to being overdriven by the tropical sunlight.

In our tanks we typically submerged the plants and immediately bombard them with mega wattage so the growth demand is high from the begining which induces algal attacks. I believe that if we keep the lighting low and nutrients/CO2 high then we are presenting a much better environment for the transition and adaptation to the submerged state while minimizing algae inducement.

"...best way to go..." is really a subjective term. Many ways can work but the science and the mechanisms of growth are the same. Check JamesC PMDD+PO4 Dosing Method for one alternative method with list of ingredients or check our Tutorials section EI DOSING USING DRY SALTS



28 Mar 2008
Guildford, Surrey, UK
I'll agree with Clive as usual.

Don't wait to start dosing, as soon as you have light and CO2 then the plants will want fertiliser.

On a 275l any name brand product is going to be expensive so I would recommend getting dry fertilisers and mixing your own. If you can't remember what day of the week is what then James has a very neat all-in-one recipe!

EasyCarbo is a Carbon additive and you shouldn't need it with pressurised CO2.

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