Why You Need A Fish Pond Bio Filter In A Small Pond But Not In A Lake?
I received the following email from Jeff, a newsletter subscriber who has a very interesting point to make. While there is definitely some truth to some of the comments, there is a very big generalization taking place.
I am also very dubious about the advice that his friend from the local shop has to offer...
This is in essence what Jeff stated in his email...
"I have been reading your emails when I can and enjoy the knowledge you share. I do have a question on this topic though.
Our local shop swears that a fish pond bio filter isn't needed and manages 15 ponds without any bio pond filter system. I decided not to buy one and for 4 months haven't had an issue. His theory is that with moving water, the proper number of plants, and fish, biological filtration can be a natural process.
He explained that there aren't filters in ponds and lakes and that there hasn't been for centuries, so why change what works. With proper setup and controls the pond should take care of itself.
If it wasn't working I would agree I need a filter but I am not sold. Have you any additional thoughts on that topic?"
My Response to Jeff...
Hi Jeff,
Thanks for your email. This is my take on things!
First of all you do not mention how big the 15 ponds are. If they are very large and have a relatively low fish loading then it is perfectly feasible that the fish and other pond inhabitants are doing just fine simply because of the large volume of water.
A large lake for example will take care of itself naturally. Due to the volume of water and small number of fish the levels of ammonia will remain low.
Take a look here...
Why it isn't possible to use biofiltration equipment in very large ponds or lakes
In addition the large surface area makes it easy for atmospheric oxygen to dissolve into the lake with very little effort, especially if there is wind present which helps to break the water service and allow oxygen in. The addition of oxygenated air however via a lake aerator pump will certainly do no harm and will encourage healthier water.
The oxygen is critically important to the fish life and the nitrifying bacteria responsible for the breaking down of ammonia and nitrite into nitrate.
This is not always the case in smaller garden ponds where there is a smaller volume of water, larger fish load and subsequently higher levels of ammonia (from fish feces, decomposing plant life, rotting uneaten fish food on the pond floor etc.) The problem with these smaller ponds is how you can effectively remove ammonia from the pond water before it poisons your pond fish and other pond life (frogs, toads) etc.
Where your friend mentions "with moving water, the proper number of plants and fish, biological filtration can be a natural process" I would first of all like to talk about the moving water.
He mentions moving water because this helps to add oxygen to the pond because it makes it easier for atmospheric oxygen to dissolve into the pond. This is why many pond owners incorporate a waterfall or fountain system into their pond.
Where your friend mentions "the proper number of plants" I believe he is talking about using aquatic plant life to form a natural filter known as a Veggie Filter; sometimes known as a bog filter or plant filter.
A veggie filter (bog filter) consists of various species of plants which naturally use up the nitrogen based compounds excreted into the pond by your fish. This system can be effective but somewhat messy.
There are advantages to using a veggie filter such as zero electricity costs, a natural system working in the way nature intended as well as green water and blanket weed control.
The disadvantages however are blocked pump impellors, a messy pond due to fish disturbing and possibly eating plants. Koi are well known for uprooting aquatic pond plants and nibbling at them.
Veggie filters also need plumbing installed in the form of a bottom drain, which should be opened every couple of weeks to allow the accumulated sludge (dead plant life, fish feces) to be removed.
Failure to do this will encourage excess pond sludge and the formation of heterotrophic bacteria colonies. Worst case scenario - fish disease and infections.
The major disadvantage of using a bog filter however is when it comes to cleaning the pond. All plant life needs to be removed and the pond needs to be thoroughly cleaned at least once a year, usually in the fall (autumn).
Why I believe a Fish Pond Bio Filter is essential in 99% of cases...
The Question is one of How To Filter Ammonia Out?
The problem with not using a pond bio filter in a small to medium sized pond with a large fish load is the sudden increase in ammonia levels, particularly during hot weather.
In hot weather the high levels of ammonia combined with the ponds inability to hold as much oxygen as would be the case in cooler weather will lead to eventual poisoning of your pond fish.
Yes believe it or not colder water actually holds more oxygen. (this is why trout need cool streams and lakes to live in because they need more oxygen than say carp or bass).
During warm spells you will often see fish gasping for air at the pond surface because there is less oxygen present.
As well as this the higher levels of ammonia (containing nitrogen) act as a food source for algae and blanket weed. These forms of plant life at night time use up oxygen in the pond water.
Whilst what your retailer friend states is true to some extent it is not always the case and in my opinion prevention is better than cure; particularly if you intend to keep expensive Koi or a high fish load in a small to medium sized pond. In this case a koi pond bio filter is recommended. Koi are voracious eaters and produce a lot of bodily waste which includes toxic ammonia.
I would advise you to take a look at the Bio Pond Filter Articles on my website. You may find them of some use. They will at the very least help to give you an understanding as to why a fish pond bio filter is critical to the success of your pond project, in the vast majority of cases and why treating ammonia in koi ponds is essential.
You will hopefully find the article explaining how a biofilter allows nature's very own Nitrogen Cycle or Nitrification Process to take place in your pond useful.
In very large ponds or large areas of water such as lakes the Nitrogen Cycle takes place naturally, without the need for a pond pump, biofilter and UV clarifier.
Take a look here...
Why it isn't possible to use biofiltration equipment in very large ponds or lakes
One further point I would like to add is that a fish pond can never have too much oxygen present. Any pond, small or large will benefit from a large oxygen supply.
I hope this helps!
Regards
Click here to see the USA and UK Pond Bio Filter Reviews on this site...