"MC" wrote in message
...
What do you mean by "low quality food"? What types of food helps keep
the nitrates low?

I don't see the food quality as having anything to do with Nitrates though
excess feed can promote a rise in Phosphates in the Aquarium
world....Nitrates are just the end product from any mature bio filter -
Ammonia, Nitrites & then Nitrates.

There are a few other things you can do to help deal with Nitrates....

1) Buy something like a Nitragon or Nitraking Nitrate filter....usually used
for tap water to prepare Nitrate free water for aquariums. You can stick one
on a pump but it needs to be quite powerfull (in aquarium terms - nothing
like a pond pump!)

2) Buy some "Nitrazorb" - works on the same principle as above but goes in
the filter (or can just sit in the water - its in a porous sachet). You'd
probably need quite a lot of it (depending on how much water you are dealing
with) and its not cheap.

Both of these are Ion exchange filters i.e. they need to be recharged with
salt water (much like a domestic water softener) periodically. Something
like a Nitragon will give you roughly 75-100 gallons of Nitrate free tap
water before it needs a recharge though you can get bigger units.

Option 3 is to run up a bacterial nitrate filter. Do a google search for
"Nitrate filter" and you will find some discussion about how these work &
links to sites detailing how you can build them fairly cheaply. They take a
week or 3 to run them up - basically you create an Anaerobic filter by
passing water through it very slowly - this becomes oxygen free as it passes
through the filter. You get bacteria building up which then eat Nitrate to
get Oxygen thus releasing Nitrogen. They can be tricky. Run it too slowly &
you get sulphur dioxide, too fast & the filter breaks down because you need
an oxygen free environment. You also have to feed the filter periodically
with Alcohol of some description (I think!)

A fourth option is to buy a sulphur based Nitrate filter. I have one of
these on a 75G fish tank which is heavily stocked & it has zero Nitrates.
This works in much the same way as option 3 above but does not require
feeding - the sulphur removes the need for this apparently. One "side
effect" of this type of filter is that it seems to strip the Kh buffer out
of the water - and does so quite quickly. As a result I add Baking Soda
(Bicarbonate of SOda) to my tank every few days. Its a bit of a pain BUT a
lot less aggravation than dealing with Nitrates by constantly changing
water. This side effect may apply to option 3 above as well - no direct
experience of use so I can't say!

HTH

rgds

Iain