On 27 Aug 2005 04:45:16 -0700, wrote:

So if I am to understand correctly, the mechanical filtration is to
keep the water in check (0 nitrates/nitrite and 0 ammonia/green water
through uv). plants for controlling algae nutrients and fluxes with ph
due to oxygen exchange/activity. does that sound correct?

Close :-)
The mechanical filtration is to remove solids. Your vortex is the first
stage of this followed by the bead filter. The bead filter has a large
surface area for bacteria to grow and this bacteria will convert the
ammonia to nitrite and then to nitrate.

The idea is that the plants then take up the nitrates in their growth
but higher plants need potash to enable them to do this and potash is
the one thing that isn't usually present in any amounts in pond water
and it gets consumed by the plants so it's the one chemical that you
really do need to add.

All the UV does is cause the green water algae to stick together and it
can then be filtered out. For a UV to actually sterilise pond water and
kill most of the bacteria you need a ridiculous amount of UV, something
like 1 watt per 5(?) gallons of water. Marine aquariums use UV at this
intensity for sterilisation but it's not practical with a pond and a
pond is open to the environment so it would be almost impossible to
keep the water sterile. I'm not a fan of UV's for a pond because the
green water algae can be a useful indicator that things aren't in
balance.

I think you need to put some potash in your pond and stabilise the PH.
If you look back through some threads I think Jan has explained how to
do this using bicarb and that will stabilise thinks quickly. Long term
you may be able to come up with a way to divert some of your water
through broken seashell or crushed coral. This is slower to act than
bicarb but will automatically buffer your PH for you since it will only
dissolve when the ph is low and as it dissolves it raises the KH and
thus raises the ph, it should then stabilise at about 8.2.

I'm surprised that you have a lot of particles floating around though
with a bead filter. They filter down to around 15 microns one they have
got running so you shouldn't have anything visible if the water flow is
correct. You should be pushing at the very minimum 1500 gallons an hour
through the filters and the outlet and inlets should be positioned so
that you have a flow across the pond from the return to the outlet so
that all of the water is cycled through the filter. If you get it
correct then with visible particles I would expect the flow through the
filter to fall in a few hours so you should have to backflush it every
day for a while at least and the fact that you have only had to do this
a couple of times in six weeks and can see particles makes me think
something is not quite right.


Have you any pics of your setup, especially with regard to the
filtration?

--
Regards - Rodney Pont
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