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New house, old pond, much trouble. (Long post with photos)

17 years ago


first Ill apologise for the length of this, my first post, sadly it is necessary. IÂve tried to keep it short as concise as possible. Basically I'm looking for some advice from the experts here, however before I begin a little backgroundÂ..

In December I moved into my new home in beautiful rural Derbyshire here in the UK countryside. The house came complete with a average sized pond, which is stocked with a mixed bag of approximately 10 fish (a mixture of goldfish, a single Koi and a couple of as yet un-identified smaller fish). I understand the pond was built with the house 32 years ago and has been stocked ever since. The previous owner of the house was here for about eight years and did not (IMHO) take very good care of the pond. IÂm very new to this, until I moved my last fish experience was when I was 12 when I won a goldfish at a fair. IÂve been learning fast but am a bit overwhelmed and could do with some assistance identifying some plants and some filtering advice for the pond.

IÂve laid out the details in as much detail as I can:-

The pond


The pond is 307cm (10.07ft) at its longest and 180cm (5.9ft) at its widest. Its 92cm (3ft) deep, the average water level is 87cm (2.85ft). For water volume calculation, IÂm assuming itÂs 3ft deep all around, which has it holding 5052 litres of water (in reality the number is closer to 4800) The pond sits in partial shade during spring/summer and more exposed during winter. The pond is lined with a very think black liner, which from the limited inspection IÂve been able to make, is in good condition.

The fish, frogs and various other garden visitors (badgers, frogs, birds and squirrels) seem happy enough with the pond, except for on very hot days when the fish seem to become distressed, hanging at the top of the pond looking for air and other rather odd behaviour. My research so far leads me to believe this is due to a lack of oxygen in the water and in turn I believe this is caused by the large amount detritus and plant material in the pond.

The pump


The pond has a single submersible pump made by Lotus, called the Mermaid 600; this claims to be 90w, have a head max of 3.45m and can pump 63.6L/Min. The feeds to the top of a small fountain and "lion" brick just above the water line at the opposite end of the pond. I set the pump running at the start of each day, when I leave for work; by the time I get home itÂs hardly pumping at all. The filters are blocked full of sludge as shown below. When clean the pump works very well, sadly it doesnÂt stay clean for very long ;-(

The pump after it has been in the pond.


The filters before and after cleaning.


IÂm wondering if anyone has recommendations for the best kind of pump to cope with such sludge. An exterior one could possibly be an option, however information on them in the UK seems to be rather poor.

The nightmare plant


The previous owner left me strict feeding instructions for the fish and an also ordered me not to remove the "green plant" at the centre of the pond, as it provides oxygenation. Fair enough, however IÂm not sure itÂs a normal plant, for me it looks and behaves very much like a weed. Either way it grows so fast, it takes over the pond very quickly. Does anyone have any clue what it is, if so, should I keep it?

I moved in winter and here is a picture of the pond as it was left for me (yes there are fish in here!)


Once spring arrived the garden exploded into life and by this time IÂd managed to almost halve the amount of this plant.


I donÂt want to cut it back 100% as it seems to house many insects and newts. The close-up here shows the plant in more detail.


Water quality, pumps & Fishy behaviour


I had the water tested at a local aquatic store, the results came back as "excellent water quality", and if IÂd have known more at the time IÂd have asked for the technical details. The fish seem healthy enough though, however weÂve had unusually hot weather of late and as mentioned earlier IÂve seen them hanging at the top of the pond appearing to gasp for breath, IÂve also seen them lie on the green plant and expose up to half the body to the air. If I go and prod around the area of the plant they are in they donÂt move at all, they will only shift if I make physical contact.



The pond currently has no filtering at all, although it doesnÂt have any algae problem, the water is very murky indeed. So much so IÂve no idea exactly how many fish I have in the pond! IÂve only been able to count those that IÂve seen feeding.

In attempt to see how bad things were below the surface I threw down a waterproof bullet camera I have for my helmet on rock climbs. As you can see from the images below itÂs very murky. The camera has a very wide viewing angle and can see quite a distance as well as excellent low light visibility yet it can see no further than about 6 inches in front of itself! Below is are some stills from fishy cam ;-)

Busy fish, but lots of debris & plant material in the water.


Up close visibility is not bad, a short distance away and we can hardly see them.


IÂve been given conflicting advice regarding the filter, however the nearest place I can put a big filter box (that my other half will allow) is 18 feet away and about 3-4 feet above the pond. Whilst the head height is not a problem for most decent filter pumps IÂm a little lost in the maze of possibilities here. Most of the shops and a couple of friends have advised I should use a pressurised filter (IÂve had the Oase modelÂs recommended by most people) Also IÂm not keen to try and make any new holes for the hose (my plumbing is always a disaster) so IÂll have to use the one that already feeds out to the "lion" brick. IÂm concerned about this, as I feel this is quite small for the job, being only 1.5cm diameter.

IÂd also like some idea if the filtering process is likely to damage the wildlife in the pond? Frog spawn, dragon fly lave etc.

For the filter return IÂll have to create a simple rock/waterfall type feature, as it will have to come over the pond side as there is no usable inlet. Any advice on the best approach for setting up a new filter system would be much appreciated. Would a gravity fed system work in this scenario? Are the pressurised filters any good?

Phew! So to sum up :-

Any ideas as to what the plant is? Should I get rid?

Any suggestions for a pump that will not clog up every day?

Any suggestions for the best method to filter the pond and if so, what impact would it have on the wildlife that uses the pond?

Well thatÂs about it for this post,thanks for reading.I hope IÂve covered everything.

I thank you in advance for any and all replies.



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