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Re: Denitrator question (freshwater) - CO2 & plants

In case anyone's interested ...

The denitrator was producing 0ppm NO3 outflow from 40ppm input within 48
hours at about 200ml / hour.

Within 3 weeks it was processing NO3 at a flow rate of 1 litre/hour & tank
Nitrates have remained at zero.

It's completely trouble-free so far (& seemingly insensitive to flow rate
at the low levels I'm using) except that it seems to also be reducing the
KH of the tank at a rate of around 1 degree / week.

I've compensated for that twice now (raising the KH from 2 degrees back to
4 degrees) but it's still happening - yesterday it was back down to 3.

The outflow KH is the same as the inflow KH though, as is the pH, (within
the limits of home testing) so it's clearly a very gradual process.

Anyone know why?

Next step is to try reducing the flow rate so that Nitrates remain low but
not zero.

Regards, Kevin

                    Kevin Buckley                                                                                  
                                         To:     aquatic-plants at actwin_com                                         
                    03/01/2003           cc:                                                                       
                    13:43                Subject:     Denitrator question (freshwater) - CO2 & plants              

Happy New Year everyone!

Someone bought me a denitrator for Christmas &, as a gadget freak with
mains water already high in Nitrates, I thought I'd give it a go (Sulphur
based, made by Deltec - see
http://www.ultimateaquatics.co.uk/acatalog/Deltec_Equipment.html for a

However I have a couple of questions that I would like to ask this learned
forum (especially Paul Sears, if you're around, & from whom I've already
learned a lot about water chemistry):

- Has anyone tried this specific method & does it really work?
- Does it have any bad / good / neutral effect on the plants?
- I read somewhere that the outflow is quite acidic & that the reason is
because one of the reaction components is xxSO4;
- Is that because it forms H2SO4 (or some other acid - is H2SO4 a "strong"
acid BTW?)?
- If the above is true (or even if it's not) how will this affect my
ability to calculate my CO2 content using the KH / pH formula?
- Does anyone on the list have a complete description of the chemical /
ionic reactions that occur in this process?

By the way, just to save time, I already know my other Nitrate reducing
options (mix mains water & RO, lighter fish load, ion xxsorbtion resins
etc.) & I've read everything about other denitrator activities such as the
DIY coil denitrator discussed on the Krib.

Background info.:

50gal tank;
Fish & plants;
CO2 injection;
Mainswater is 30ppm NO3, GH=16, KH=5;
Water change is just using mains water when the tank Nitrates start to get
too high (remember, they start at 30ppm!).

Regards, Kevin