The Koi Pond Project
Filtration and the dreaded Ammonia and Nitrite
New Filter Syndrome.
Having constructed my new filter and installed all the media and filled
the system with water I turned to making the water safe for my new fish.
After three days there was zero Chlorine and of course, with no fish, zero
Ammonia and zero Nitrite.
I had a full new set of fish coming.
This isn't really a good idea.
If you introduce fish gradually it gives time for the filter to accommodate
the changes in load.
I had bought a job lot at a job lot price and I had a deadline to collect them
by.
The race was on!
Firstly I dosed the water with Ammonia solution, to simulate a large fish population.
Then I bought various filter start preparations, including, or so the labels
said, the necessary bacteria.
The plan was to get the required bacteria up to speed before the fish arrived.
It was only partially
successful.
It's really very simple and can be found everywhere, but here's my
summary:
Fish excrete Ammonia.
Ammonia is a strong alkali and very toxic to fish.
In high pH water, "free" Ammonia exists in the water - very bad.
In low pH water, the Ammonia is present as Ammonia (Ammonium) salts and is
far less hazardous.
Bacteria such as Nitrosomonas oxidise Ammonia into Nitrites (NO2).
Nitrosomonas multiply quite quickly and the high Ammonia levels should fall
away quite quickly as a result.
This part happened
in my new filter management plan.
Nitrites are also very toxic to fish. As the Ammonia is oxidised
to Nitrite, the Ammonia levels will fall and the Nitrite levels will
shoot up.
They can quickly stress the fish and weaken thier immune systems - I
know, I've learnt the hard way.
Nitrites can also combine with haemoglobin in the blood in a similar
way to Carbon Monoxide (brown blood disease), reducing Oxygen uptake
and weakening
the fish further.
Unlike Ammonia, Nitrites are much more toxic in low pH water and less
toxic in high pH water.
My fish fatalities have been due to opportunistic bacterial infections
taking hold because the fish are weakened with poor immune response.
To reduce the toxic effects of Nitrite, salt can be added (reduces the
uptake of Nitrite in gills I believe) and repeated water changes can
be made.
These help, but don't replace bacterial action and can't be succesfully
used other than for very short term - again, I learnt the hard way.
Bacteria such as Nitrobacter further oxidise the Nitrite to much, much
less harmful Nitrate (NO2 -> NO3).
Here is the bad news.
Unlike Nitrosomonas, Nitrobacter are very slow to multiply.
In my case,
the various products I bought claining to contain live bacteria had no
effect at all on Nitrite levels.
Adding a few and waiting for them to multiply won't work unless you have a
very small fish load.
I spent a lot of money on Koi filter products and was unable to reduce the
Nitrite levels at all.
My time was now up and I had to add my new fish to the pond and was now desperate
to get the filter "mature" ASAP.
I tried yet more products to try and tackle the Nitrite (without chemical intervention),
but again was failing.
Only the water changing was keeping the Nitrite below 1.0mg/litre (still way
too high!).
Finally I approached a biotech company who sold me some bacteria that
were:
• Alive on arrival and "deployment".
• In large numbers
• Able to half Nitrite levels overnight.
More to come.......