Dear all, please can someone help- I have an 8ft by 3ft railway sleeper pond which is lined and is 3ft deep. It has an OASE NEPTUN 5000 85w pump, a FISHMATE 15000 UV+bio pressurised filter, and an OASE AQUA-OXY 400 air bubbler. I also have 2 floating pot-plants. However, over the 2yrs the pond has been in use, all the fish have died, most with no obvious signs of problems. I had goldfish, koi, shibunkin, orfe, tench, grass carp, and ghost carp. These fish all lived happily in a much smaller pond I had dug in the ground at my old house with much less powerful equipment. They also survived for several months in a large paddling pool while I built the existing pond! I had the water tested a while ago and was told it was high in nitrates, so I reduced feeding and introduced the plants and carried out regular water changes. None of this helped. The pond is now empty and has developed a large stock of weed. Any ideas why I can't maintain a viable eco-system? I love having fish, but I'm considering turning my pond into a veg patch if I can't keep them alive! All advice welcome. Thanks.
MyLittleAquarium- no, the sleepers are untreated, they were new and not reclaimed so should not have any harmful products within them.
2010- the max flow rate of the pump is stated as 83 l/min (which sounded like a lot to me!). The volume of my pond is approx 507 gallons (2304 litres) using the exact internal measurements. The filter has a max flow rate of 7500 l/h (125 l/min). I'm not sure where you're leading me here. Is the equipment mis-matched? I went to an aquatic centre with my pond dimensions and this is the stuff they reccomended. Again, thanks for your help.
I think you will find the filter has a max flow rate of 9000L/H. Most sites show pond size up to 15000 litres (3300 gallons), but some also state Goldfish ponds 7500 Litres (1650 Gallons) and Koi ponds 3750 Litres (825 Gallons).
The pump is as you say 83l/m or 5000l/h.
If your internal measurements as stated in your original post are 96" x 36" x 36" the volume would be only 2038litres (448 Gallons). What are your exact internal dimensions? I think I already know what you are going to say but need you to confirm. Thank you.
But ideally you should know why what you have does not work, not just the fact it does not work.
I came up with a slightly different figure for your pond volume (it really was only slightly different) so lets split the difference and say your pond is 2000 Litres.
I was hoping you were going to say the pump rate in LPH not LPM, then it would be more apparent.
Your pump 5,000 LPH Your pond 2,000 Litres
Do you see where this is going? Being realistic the pump will only pump 5,000 LPH at zero head, so lets say 4,000 LPH at what ever head you have.
So that means your pump can send the whole of your ponds 4,000 litres through the filter twice every hour.
Most koi pond owners (with a reasonable stock level) send the water through their filters once every two hours. So yours is going through 4 times as fast as the max, ideally you should be aiming for once every 4 hours.
Your filter itself has lots of capacity (it could be argued its too big (it is if you read the specs)
Specification: ? Suitable for ponds to 15 000 litres (3000 gallons). ? UV Rating: 13W ? Dimensions: L x W x H = 390 x 280 x 430mm (15.5? x 11? x 17?) ? Maximum flowrate: 7500 L/H (1500 GPH) ? Pond size: 3750 - 15000 Litres (750 - 3000 Gal.)
You can never have too much filtration, but the flow rate can be too fast.
In short, the good bacteria in your filter do not have enough time to do their job. I would be inclined to buy a couple of box filters and connect them in series, (or a very big box filter) so it gives the bacteria more time. The Neptune 5000 is a feature /fountain pump, not a filter pump, perhaps you may want to change that too. (but for the time being you could turn its flow rate down.
One more thing, you need to get yourself a test kit, so you can test the water on a regular basis yourself. (Some one here on the forum has mentioned a good place to get them, try a search)
And finally, shops are there to make money, forums are here for advice.
Good luck and please post a picture of your pond.
Good quality costs. Bear this in mind before you start.
Sorry if my reply is NOT want you want to hear, but what I have said is true.
OK, actual internal pond measurements are L 94in/239cm, W 45in/114cm, D 33in/84cm. This gives a volume of 2288.664L, so let's say 2300L for the sake of argument. From what 2010 is saying I guess I need a pump with a max flow rate of between 575l/h (9.5l/min) and 1150l/h (19l/min) but preferably nearer the lower figure? I'm assuming the flow rate of the filter should be similar. Am I right in thinking that box filters are gravity-fed? because this would present a problem as my pond is a raised one. My only other questions are- should I clean my pond out before I replace the kit, or allow the new kit to clean it over time before stocking? And what amount of fish will a pond of this size sustain? Thanks again for all the advice, the knowledge levels on this forum are very impressive!