Re:How to build a cheap sump wet/dry for your plant tank

[Chuck Gadd <cgadd at cfxc_com>]

Adam wrote:

> overflow systems with pre-filters weren't necessarily a good thing for
> plant tanks due to the fact that they're more likely to drive out CO2
> from the water?

Yes, they are more likely to drive out CO2, but how much more?  Not
much in most practical experience.   George Booth has an excellent
article that he did that measured the CO2 loss, and it wasn't nearly
as much of a factor as most people had long suggested.

> to weigh up whether they want to spend a lot of money on huge canister
> filtration, and additional biological filtration systems (maybe
> fluidized bed or something) to bring the filtration up to the same
> standard of the much cheaper (for large systems especially) and highly
> efficient wet/dry system 

Well, one big thing is that in a heavily planted tank, massive biological
filtration isn't needed.   The plants do most of the work in eliminating
the ammonia.  Besides the great bio-filtration offerred by the wet/drys,
the sump in the wet/dry system provides space to remove equipment from
the tank (like CO2 reactors, heaters, etc).   I like my wet/dry mainly
for the fast and easy cleaning.  Also, in the dry air in Denver,
evaporation can lower the tank water level by a few inches each week.  With
a wet/dry the tank water level always stays the same, only the water level
in the sump drops.

> and just 'bite the bullet' when it comes to
> having to replace the lost CO2? Then again, here where I am, compressed
> CO2 systems are very expensive for some reason - my main supplier sells

But the compressed CO2 system would be needed on a larger tank, regardless
of the filtration method used.    The slight increase in CO2 used translates
to a few dollars extra per year in wasted CO2.