FAQ

What sort of fish should I choose for my pond?

There are many varieties of fish to consider, such as goldfish, Koi, Rudd, Tench, Shubunkins and Orfe to name but a few. Your choice may be affected not only by your individual preferences, but also the size of your pond and whether or not you have a filter system installed.

Another important factor of course is how large the fully grown fish will become. For instance, the Koi and Orfe will grow too large for the smaller garden pond and they also require a high quality of water, although given the right environment, these fish can certainly thrive in your pond.

How many fish can I have in my pond?

There is a simple mathematical calculation we use to work out how many fish you can comfortably fit in your pond. Multiply the average length of the pond by its average width – this will give you the surface area. Apply a general rule of 1 inch of fish to each square foot – or if you’re metric-minded, that’s 25 cm of fish per square metre.

Also, remember that it is always preferable to have slightly fewer fish than to have too many. This is because fish are more active in the summer and there’s less oxygen in the warmer water than in the colder seasons, so resist the temptation to over-stock the pond.

Is there a right time of year to stock my pond with fish?

Yes, but the time period is quite broad. You can add fish from the spring through to the late summer, when the water’s warmth is at least 10 degrees (50 degrees F).

How do I remove blanketweed or string algae from my pond?

Blanketweed or ‘string algae’ as it is called is a huge problem for goldfish and koi ponds and not uncommon. This green algae grows abundantly in ponds full of life and becomes particularly invasive in those ponds that are not as well maintained. If untreated, blanketweed will quickly grow to cover the whole surface of the pond in just a few days or weeks. The result is an ugly-looking pond with no fish to be seen.

As blanketweed is an algae, it responds to food nutrients like nitrates and sunlight. As a long lasting solution, we only recommend an I-Tronic solution that gets rid of the blanketweed by ionising the water with electronic copper. This controls and will kill the blanketweed in less than a month. With I-Tronic, there is no need for powder or liquid and once you’ve installed it, it is cheap to continue to run. You just need to replace the electrode as needed.

Do I need to use a filter in my pond?

Whether you need to filter your pond or not is often the subject of much debate and there is always someone claiming they have managed to let their pond ‘go natural’ without interference from man at all. However, a pond that is man-made is not the same as a naturally occurring environment and so it needs at least aeration if not some sort of filtration.

Filtering will keep your water free of organic waste that can then cause smelly, cloudy or water that is actually toxic to fish. Filtering keeps your pond maintenance simple; conserving water through recycling and means you are more likely to have the clear water you want to give optimal viewing pleasure of your pond and any fish in it. If all you want is a water garden with water plants, then you are more likely to be able to cope with less filtration; this will depend on the type and quantity of the plants in the pond.

Usually, a smallish pump with a fountain, spitter or other such feature will create sufficient movement to avoid water stagnation. Removing dead or decaying plant life will help keep water clear. Once they have a pond though, most people decide they’d like to add fish; in this case, filtration is vital.

Fish produce ammonia, as does more organic matter decaying in the pond. The greater the number of fish in the pond, then the higher the level of filtration you need to keep both water and fish healthy. Ammonia is poisonous to fish so it is vital this is removed. Changing the water or making use of water conditioners to bind the ammonia offer temporary relief, but certainly the use of biological filtering is the easiest and best method for ammonia removal.

How does a bio filter work? When do I start/stop my bio-filter?

To summarise, a bio filter creates the right living environment to encourage certain bacteria that will then do the water cleaning on your behalf. Pond water slowly pumps through the biofilter, then Nitrosamines bacteria eat the ammonia, which is then turned into nitrites (these are still harmful to the fish). Nitrobacteria bacteria will now oxidise the nitrites, which then become nitrates. These nitrates are good food for pond plants.

On every pond surface, such ‘good bacteria’ is indeed present, but not normally in sufficient enough quantity to remove these deadly compounds from the water.

What about mechanical filtration?

Mechanical filtration will remove solid waste from the pond. Although this is certainly a good idea, in itself this is not enough to guarantee the water is safe for the fish. It is only by using water test kits that you can detect both nitrites and ammonia. In an ideal world, the water will pass through a mechanical filter first to remove solids, then through a bio filter to oxidise the toxic compounds before returning the water to the pond so the pond plants can absorb the nitrates.

How long does it take to begin a new filter system or start again after the winter?

Once the warmer temperatures return, the bacteria start colonising. The entire nitrogen cycle takes up to 6 weeks to get going, so you should be careful to test your pond water for nitrites and ammonia if the pond fish have started eating.

What sort of filter do you recommend?

There is a lot of information and detail on the different filter types on the market. Therefore, if you have any other questions, then please feel free to contact us at Perfect Ponds. You shouldn’t believe every manufacturer’s advertisements.

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