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

["Adam Shaw" <adams1 at comcen_com.au>]

Just wanting to see some other opinions out there, but I have always
thought that wet/dry filters, trickle filters and even to some extent
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?

CO2 is not highly soluble in water on its own, and is readily driven out
- more so even than oxygen is due to its larger molecular size (larger
than H2O molecules as well as O2 molecules).

As a general rule of thumb from where I come from out here (on the
Australian East Coast), most aquarists here that I have talked to,
including many FS's are anti-trickle/wetdry filters on planted tanks for
this reason, and promote canisters, and to some extent hang-on filters
(though some even do not agree with these as they believe these can also
contribute to CO2 defficiencies). 

If these filters do drive out the CO2, then maybe the compressed CO2
system or DIY yeast or whatever is being used, may be operating in
adverse conditions... Or maybe there is a point where the individual has
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 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
Dave Gomberg's system for $285.00AUS.. If you want self-controlling
stuff then you're looking at $550.00AUS minimum and you still have to
add your own celenoid and pressure regulators etc! And that's the
cheapest supplier too... Plus finding a local welding supplier which has
all the fittings and necessary precision valves here is like attempting
to push a mach truck up a hill. So I guess we're more conservative when
it comes to pressurized CO2 addition :)

I'm running canister filtration as well as a larger Aquaclear 500 on my
270L planted discus tank (umm that'd be about 70G for the yanks and the
rest of the world that hasn't caught up to the SI Metric system yet :)).
Tank contains many Anubius plants (Anubius nana, barteri, 'emerald
heart', afzelli, as well as some large hybrids), plus some ozelot swords
(Echinodorus ozelot), Oriental swords, and with some Rotala rotundifolia
and some forms of Hygophila spp. I'd love to know ideas on the wet/dry
stuff as it would be much more beneficial for my beloved discus to have
the luxury of the wet/dry filter! At the moment I'm looking at fluidized
bed filters for biological - canister just doesn't cut it! It's all $$$$
and added maintenance time....

Any ideas out there?

Cheers,
Adam Shaw