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Re: 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 ludwidgia
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."

Is the UGF powered by air or by powerhead? No biological filter should be
"turned off" for more than a few hours at a time and then turned back on
again. They depend upon a steady flow of oxygenated water flowing through
them and turning them off will quickly cause the bacteria to suffocate, die
and cause problems.

Water (and water borne nutrients) can enter the substrate through several
mechanisms - the use of an UGF is one way to do it and provided that the
flow rate is kept low, it can work. Water will also diffuse into and through
a substrate but this is a slow process and can be impeded by particulate
matter in the substrate. Plant roots can also help in pulling water into the
substrate and they also release oxygen into the near vicinity. Plants with
strong root systems are better at this than those with fine root systems, at
least the effect would be more noticeable. It might be that when you turned
off your UGF during the day, substrate conditions deteriorated rapidly in
those areas where the fine rooted stem plants were growing, causing them to
do poorly and die but the more strongly rooted plants were able to overcome
the problems better and so survived.

I have had many successful planted tanks without any active artificial
mechanism of substrate water circulation (i.e. no UGF).

I wouldn't worry about the loss of CO2 - its a trade off. So long as you are
adding CO2 at a steady rate the plants should still be able to scavenge
enough before it escapes into the atmosphere. Either that, or replace the
UGF with a sealed cannister filter which can run all the time and not cause
surface turbulence.

James Purchase