I have never hidden that fact that keeping Nishikigoi is a costly hobby and the more enthusiastic one becomes, the costlier it gets. In fact, regarding the expense required, there are no limits in the hobby.

Keeping any form of livestock produces some bad experiences along the way and keeping livestock that need to be kept in water is far more of a challenge than keeping livestock in the air that we breathe.

I have been keeping Nishikigoi since 1972 and I believe I now have some small idea as to what I’m writing about.

This shows my own Koi pond today – it holds 16,500-gallons (75,000 litres) of water, it is 2.35m deep and the pond base has four bottom drains that link by gravity to an in-ground filtration housing built behind the waterfall.

It has been in running operation from late 1999 to late 2009 when it was closed down, but it was re-opened in late spring 2013 to date.

The reasons I closed down the original system was because of the sheer expense of running the system.

These next three shots show the original filtration system and all equipment items required.

Without going into fine detail, the initial purchase price of the items required in the original filter house exceeded £12,500.00 and that does not include the labour costs of installing them as shown.

The internal dimensions of the filter house are 10 feet wide by 30 feet long by 8 feet high and I needed all that space to accommodate all the items required.

I used gas heating for the pond in winter so that was separate, but there were nine large water pumps running, two powerful dehumidifiers, four U/V units and eight air pumps.

In short, annual electricity costs for the pond only – were £12,000.00, hence the reason I closed down the pond for four years and was seriously considering filling it all in.

My change of mind came about in spring 2013 when I decided to use the pond as a test bed for my Eric filters, so we (that’s Ian Miles & my wife Hilary) cleaned out the pond thoroughly and started again with a brand new filter house.

Instead of running each drain line to an independent filtration system I decided to control each drain line by ball valves to ensure that the single filter planned could take water from each of the bottom drains by alternating the valves.

This is the new pipeline layout –

Because the pond is gravity-fed from the bottom drains and the filter was much shallower than the original vortex units a filter stand was required –

The first Eric filter hooked up to the pond was an E4 unit – the largest in the range and is specified to handle 7,000-gallons of pond water. At the time I had serious doubts that it would be able to handle a pond of this volume.

I used the E4 filter for the first six months to find it handled my pond perfectly but by then my thoughts were that a much smaller Eric filter could probably do exactly the same job?

In early 2014 I replaced the E4 filter that contained six eMat cartridge blocks with an E2.5 filter that only contained three cartridge blocks.

For demonstration purposes, the filters I use are made from clear PVCu in order to see what is actually taking place inside them.

Since then, my pond has been running perfectly with one single-tier EPDM brush box as the mechanical stage and three eMat cartridge blocks to take care of the biological stage.

To put all this in perspective, instead of running four filter systems – I’m running only one.

Instead of running four ‘high energy’ filter pumps I’m using one ‘low energy’ filter pump.

Instead of using three skimmer pumps I’m using only one.

Instead of using eight air pumps I’m using only three.

Instead of using four independent U/V systems I’m using only one submersible U/V in the waterfall header tank –

I no longer need expensive dehumidifiers.

Regarding the maintenance aspect, with the original system it was only possible to clean two systems per day and it took two guys a whole day to do this as far too much good water was wasted and it took many hours before the pumps could be re-started.

With this system I can clean the entire filter in three minutes and have it running again immediately.

The water discharged to waste is replaced slowly and safely by a constant ‘trickle’ of mains water.

Depending on the time of the year, gnat larvae and algae can obstruct viewing inside the clear filter, this means stopping the filter, removing the brush box and three cartridge blocks then removing the obstructions with pressure hose or cloths.

After that the brush box and cartridge blocks are replaced – this takes around 30-minutes to complete around every six weeks.

Total electricity running costs of the new system are now around £1.50 per day or £550.00 per year – this represents an annual saving of £11,500.00 per year with the original system.

The time required in maintaining this system properly, when averaged over an entire year, makes feeding the Koi MUCH more time consuming.

The foods fed to the Koi consist of a ‘homemade sinking porridge’ – all ingredients are for human consumption.

My reasons for this are two-fold – I believe that Koi (carp) prefer to feed from the bottom of the pond and this particularly messy food recipe will mean that the filter system has to work much harder.

‘Water clarity’ in an outdoor pond also can produce many issues; on my pond I can see everything right down to all items on the pond base at all times of the year.

Is it ‘Gin Clear’ or ‘Crystal Clear’?

No, purposely it’s not; in warmer climes keepers place roofs or shades over their ponds in order to prevent serious damage to the Koi by sunburn.

In outdoor UK Koi ponds this also takes place – but only in the ponds that have ‘Crystal Clear’ water.

Thankfully, the mud ponds in Japan are not plagued with crystal clear water!

Water quality readings have never been a problem with this system.

Finally, keeping Koi will always be costly, but it does not need to be anything near as costly as we once believed!

Peter Waddington.

November 2014.