Any disadvantage to an over-rated pump?

Not always true.

if water goes too fast through a UV the uv will be a waste of time.

Of course it depends how big the UV is.

But yes it is nrmal to go pump>uv>filter

The idea being the UV causes the algae to clump together and is then caught in the filter.

so to remove it is not a good thing.

 

Hi water-garden. My statement was based upon the supposition that all components are matched. Cheers...freddy.

 

Even if it's only getting a fraction of the water? That's what seems really odd - the UV is attached to the 2nd filter that is handling a fairly small fraction of the water. We were thinking it might be easier to maintain if we simplified things so that we were at pump > uv > filter, and it was one simple loop so ALL the water went through the UV.

We can't quite work out WHY that 2nd filter is there at all to be honest as the Biotec should be more than adequate for the pond volume (even assuming we're conservative on the volume and allowing for some fish). All we can think at the moment is that the UV/2nd filter combo were put in when the pond was first built but weren't sufficient (possibly couldn't handle enough flow - the UV is only 1"), so they added the Biotec but figured having the 2nd filter wouldn't do any harm...

 

Hi Tangle. Based on your estimate of 4,000 litres ,which is not far off 1,000 gallons, you need at least 10 watts of U/V in operation. To be on the safe side I`d go for 20 watts which is a 2 footer. ALL the water needs to pass through the U/V, bearing in mind that the flow rate needs to be right. Too fast is not good. But, it seems you have that side of it covered(the pump) Cheers...freddy.

 

BTW Tangle, you can`t have TOO much filtration or U/V. Cheers...freddy.

 

Tangle, I should have asked at the outset, is it your intention to keep KOI ? Everything I`ve said so far was based on that assumption, sorry if I assumed wrong. Cheers...freddy.

 

Hi Freddy - no, koi don't feature at the moment. We inherited the whole kaboodle, complete with an assortment of c. 35 fish (2 common carp, a roach, a bream, a couple of rudd and lots of goldfish). We lost a few of the goldfish this year, but if we put anything else in it'll probably be along the goldfish/shubunkin line rather than Koi.

 

Hi again Tangle. Having checked out your filter (Oase Biotec 5)it seems perfectly capable of handling what you already have. I would however be careful before adding more fish as filter ratings can be misleading. The phrase `up to` is key in this regard. If I were you I`d add a decent U/V to the system then monitor the water quality before adding more fish, preferably when the water warms up(filters are not very active at this time of year). Cheers...freddy.