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Re: Does liquid fertilizer sink to the bottom without filtration?

> Subject: Does liquid fertilizer sink to the bottom without filtration?
> I have a 2 ft fully planted aquarium with 72 watts lighting, runs on UGF
> DIY CO2. In the past, my aeration was turned on all day and daily dose of
> liquid fertilizer was added. Stem plants like didiplis diandra and
> repens thrived well in my tank. Then I learnt that surface water movement
> can eliminate content of dissolved CO2 in water. And so I turned off my
> aeration completely when I turned on the lights, and vice versa.
> Coincidently or not, my stem plants like those mentioned above began to
> slowly die off despite daily doses of liquid fertilizer. However, plants
> like nymphaea lotus, sword plants and deeply rooted plants are still doing
> great. My deduction would be that since there is no circulation of water
> the day, all the liquid fertilizer would gather into the substrate and
> therefore the stem plants absorbed very little nutrients through their
> leaves?

An explanation for this phenomenon could be that without the water
circulation, the stem plants experience a hard time getting their nutrient
requirements. It is known that the thickness of the diffusion layer
surrouding the plants will decrease when the water movement (turbulence)
increases. This would be much more important for the stem plants, who rely
on nutrient uptake via their leaves, than it would be for rooted plants such
as Echinodorus and Crypts. The best solution to this problem therefore would
be to install a pump that ensures a good water movement without too much
surface agitation by e.g. installing the filter outlet a few cm (or inch if
you want :) ) unther the water surface.