Filter advice please

[historyman999]

I am very new to this forum, having only just discovered it.
I have a raised pond of some 3500 litres which has 2 ghost carp about 25 cms, a large goldfish about 27 cms and 8 other goldfish all around 7 cms. When I set up the pond a year or so before Covid hit, I bought a Hozelock Revolution 6000 pressure filter and pump. This has worked perfectly - until now! No matter how many times I turned the handle to clean out the gunk, the pond has never gone back to the usual crystal clear. Having looked on You Tube (where else!), I opened up the filter, preserved the plastic bio bits in a bucket of pond water, and cleaned out the foam cubes with tap water (they were full of gunk) and then soaked them in a bucket of pond water before putting them all back. The container also had half an inch or so of gunk at the bottom and I hosed that out as well.
Whilst is was apart, I replaced the UV lamp and then put it all back together again.
This was a week ago and I was rather expecting the murky water to clear again, but it hasn't. I have turned the handle a couple of times in this last week, and the water coming out wasn't that bad.
Therefore, I have decided to go for the good old box filter with a UV lamp and use the pump that I have. There are so many on the market that I am confused (and at my age, that doesn't take a lot!). I know that the box will need to be higher than the top of the pond, and that isn't a problem.
I would very much welcome your advice an which box filter to purchase. Many thanks.

[The Moo]

To clarify, it is just the outlet of the box filter that needs to be above the water level of the pond. So if the outlet is at the top of the box, it need not sit so high.

I suspect using tap water to rinse the sponges and presumably hosing out your pressure filter may have set it back a bit, so it may take a bit more time for things to normalise.

In addition to my own, I help maintain my sister in law's pond which has a pressure filter and find that relying on the handles alone does not cut it at all, so we are frequently stripping it down and cleaning everything, but always with pond water and getting pretty good results in terms of clarity and water condition.

If you are determined to change to a box filter, I am sure someone on here will advise you on what is currently hot and what is not. ( I have not had a box filter for many years so a bit out of touch with things)

[historyman999]

Many thanks.

[pacman75]

I've got kockney koi box filters and they work although any box filter are a hands in experience. Have you thought about maybe a 2nd hand easy pod as this would cope with your pond and I believe work well and easy to clean

[historyman999]

Thanks. I haven't heard of an easy pod so I'll look into it

[boiled-egg]

Box filters are pretty much all the same, some mechanical filtration and some biological filtration. They all have different media each claiming to be the best.

What really matters is the duration of the water in the filter, so if the filter is small and the pump has a high flow rate, the filter will take a long time before any visible effects are noticed. The opposite is also true, a slow pump rate and a big filter should have a noticeable effect in a week or so.

All filters need maintenance, which in most cases involves removing any amounts of "crud" both from any sponges (and or brushes) and the media. This should always be done in pond water, never with a hose from a tap. (In so doing you kill all the good bacteria) Some people put the media in "onion sacks" so the media can easily be removed and rinsed.

Part of the maintenance is to change the UV lamp at the beginning of the season, and while doing that check the condition of the quartz sleeve (It should be clear)

Pump fed box filters must have the pond return above the height of the pond, gravity fed box filters (Don't see many of them) must be higher than the pond, so if the pump stops the filter can not overflow.

I have found that if you ask 10 pond owners which is the best (box) filter, you will get 10 answers, no two the same.

[historyman999]

Thank you

[Guppy]

The gunk is what's being suspended in the water, being drawn in by the pump to the first part of the filter- thus, gunk. There's got to be a reason why there seems to be so much. New fish or plants ? Or, don't laugh, you have closed the dirty water valve properly, done it myself.
I suspect the filter is being over worked for some reason and if you're happy with it operation, i run a Hozelock Revolution, maybe have a look at upgrading, filter size and pump. You cannot overfilter fish environment.
Look at it this way. A 3 liter engine car can do 30 mph as can a 1.0 car, but the 3 litre just does it easier.

[historyman999]

Now that sounds very reasonable and I'll check the valve. Thank you