For starters, I’ve learned so much more about how my filters work and I’m still learning because there are so many options available.

The E2.5 filter replaced the earlier and much larger E4 filter in late 2013 and I have found the aerated base on this to be a Godsend.

It is absolutely superb, there are a couple of small air seepages from the base seal but this does not affect the air supply and perhaps this is because of the huge 200lpm air pump I’m using?

(I’m planning to trial a new aeration idea soon).

With double the amount of surfaces and only half the length of the unit, the water quality readings are exactly the same as before – pH 7.4; ammonia – 0, nitrite – 0 and nitrate at 10.

However, I’m convinced there must be a ‘slight’ ammonia reading from time to time.

I’m now dumping only 88 gallons of water to waste with each discharge, instead of 125 gallons but I’m still using the constant trickle of new mains water.

The back-siphon through the switched-off pump now allows me to slowly re-fill the system from the pond after I’ve carried out a full discharge.

This is extremely important to the flushing process as the back-siphon water is heading straight towards the brush box and drain, it will not allow any trace of waste to go back into the bio section during or after a discharge.

The filter discharge outlet valve to waste is now usually opened to around only about a 2” bore and this gives me time to brush the front face of the EPDM brush box slowly and much more thoroughly.

My daily regime of maintenance is to first isolate the filter and dump all four drains into the discharge box until it is full to the brim; I’m estimating that this means 100-gallons of water.

When this is completed the filter system is completely discharged to waste – add another 88-gallons of water.

I’ve timed this and the entire pond service and filter discharge takes 5 minutes to complete, but in view of the huge size of the pond and the tiny size of the filter I am doing this twice per day.

Dumping 376-gallons to waste per day still only represents a 2.27% daily water change.

Right from the outset of these tests I decided to supply the brush box with as much ‘sloppy and messy food’ as I could muster.

For much of the time I’ve intentionally fed the Koi with pre-soaked and very soft sinking pellets together with finely chopped mussels, finely chopped tuna and also finely chopped prawns.

As you may guess this produces far more ‘bits’ in the pond water than standard Koi pellets do, but the test would not be a real test of the brush box if standard Koi pellets were used.

Also the waste produced from this ‘sloppy food’ is only ‘a small part’ of the total debris that finds its way into the outdoor pond.

Through experience of the operation, I have concluded that one single brush box is FAR better than multiple brush boxes – it also happens to be cheaper.

I have been using this discharge method for many weeks now and I can’t see any need of EVER removing the brush box for cleaning!

Here’s a shot of the pond debris directly before the EPDM brush box –

Here’s a shot showing that no debris can be seen after the brush box –

The water being returned to the pond is – well judge for yourselves –

For some time now, I’ve been feeding all four bottom drain lines directly into the brush box, so that means (on this pond) that one single EPDM brush box is coping with 16,500-gallons of waste from a huge pond base.

This would never happen in a real-life situation, but it does go to prove just how efficient a single EPDM brush box is in achieving excellent water clarity.

In truth, my brush box, running for just one day is working four times harder than in a real-life situation.

Right now, I can leave the brush box for five days before cleaning, but please bear in mind – this would be twenty days in a normal installation.

THE MAIN REASON FOR THE ORIGINAL TEST WAS TO PUT THE ERIC FILTER THROUGH REAL-LIFE SITUATIONS THAT COULD NEVER POSSIBLY ARISE IN A STANDARD KOI POND SET-UP.

THE VERY THOUGHT OF 16,500 GALLONS OF WATER BEING FILTERED BY A BOX CONTAINING ONLY 88-GALLONS OF WATER, ONE SINGLE BRUSH BOX, THREE eMat BLOCKS AND A SINGLE LOW ENERGY WATER PUMP WOULD HAVE BEEN RIDICULED ONLY A FEW MONTHS AGO.

THE CORRECT WAY TO FILTER THIS FOUR-DRAIN POND WOULD HAVE BEEN TO CONNECT EACH DRAIN TO ONE FILTER AND ONE PUMP BUT THAT HAS ALREADY BEEN DONE AND IS ALREADY PROVEN BY MANY OTHERS.

THE BEST NEWS OF ALL IS THAT I’VE SERIOUSLY UNDERESTIMATED THE HANDLING CAPACITY OF ALL MY FILTERS!

I MUST point out here, that a single filter that only holds 88-gallons of water is 187.5 times SMALLER than the 16,500-gallon pond it is filtering!