pumps and filters

[Bonzo]

looking to buy a new pump and filter this year, can anyone recommend a make etc , my pond is approx 17ftx12ftx3.5-4ft deep and well planted to a shelf all the way round its border, the fish population is approx 70-100 1oz-5ozs size fish.any advice welcome

[ColinW]

Make your own filter, the ones they sell are very expensive. I tried a few variations before I found a solution that works well, here it is

 

 

Oops, I forgot to put on the water feed pipe, which comes in above the foam prefilter. The pipe I did draw is the exit pipe.

The idea of this arrangement is that the gravel that forms most of the biological filter is always completely underwater. The water travels down through the filter and then up the pipe and out. As the foam prefilter becomes blocked, the water level rises, until when it's completely blocked the water flows down the overflow (hopefully this doesn't happen because you clean it out now and again!) The box is a big black plastic loft tank with a lid, I got really lucky there we were throwing it away at work! I am operating it much deeper than it's designed for but although it does bulge a bit it's not shown any sign of bursting and it's been operating for ten years now. The pipework is 2.5 inch pvc wastepipe. The pump I use is an Otter model that is no longer made, it's been running with no maintenance for years, I don't know if their new models are the same quality. The gravel is washed pea gravel from a builders yard, there are lighter, dearer alternatives. I suppose you could rob gravel off the local beach in some places! The only thing I got from an aquarists is the open cell foam, I wanted to make sure it was safe, stuff sold for other purposes probably has chemicals added. It's also a much more open foam than the types used in furniture, so it doesn't block up too quickly.

You don't need a massive pump, because obviously it mustn't deliver too much for the overflow to deal with (which is actually quite a lot).

Keep the inlet and the outflow fairly close together in the pond. That might sound daft but believe me, water lilies grow much better without a current.

[Steve Walker]

I agree with Colin, those coldwater loft tanks are perfect.

 

The ideal setup is a bottom drain in the pond that feeds the filter by gravity - you then put the pump on the clean side of the filter and pump the water out of the filter and back into the pond. Having your pump on the clean side means that it never needs unblocking. Not easy if your pond is already built, though, in which case you are stuck with pump in pond. Have a look for low pressure pumps with big solids handling capacity, to minimise the amount of time you have to spend de-crapping the pump.

 

Gravel is a really good biological filter medium, however it has the significant downside that it tends to block if you don't have really good solids removal first. Personally, I would go for a plastic biological filter medium such as Flocor. It's expensive, but it never blocks. I would also consider using a primary settlement chamber with brushes before the biological filter - just a tank full of water with tightly packed filter brushes hung in it. As well as providing very good solids removal, they provide another large surface area for biological filtration. If you do this, put a drain in the bottom of it with a tap or standpipe, so you can flush the solids out of it easily.

[Bonzo]

thanks guys i will give this a bit more thought

[Now there's a right un.]

My Pond is of very similar dimensions to yours and I use the Oase Bitron.

It has a large UV light. Double water input with adjustable flow rate.

It also benfits from a large containment unit and easy use drainage port.

The filtration sponges can be easily cleaned.

 

I have never had issues whilst using this.