Simply Koi and More Koi

Hello ....
Im changing over from a 300ltr home made filter to a nexus200 ive had my 55w uv before the filter. (IS THIS WRONG) Ive seen both .before and after the filter .. my reasoning for before was algae and bad bact been boshed before it enters the filter giving the filter less work to do .... could I please have your options and of course reasons why . Thanks lee

The position of the UV depends on whether you are pump or gravity fed, which do you have?

Hi there . Im pump fed mate

In that case, you have no option. Neither the nexus nor the UV can go before the pump so they must be fitted after it which means that the Nexus has to flow back to the pond by gravity and it won't be able to do that if it has to flow back via the UV. Therefore the only way it will work in your situation is for the UV to go directly after the pump with its outlet feeding into the Nexus.

If you install a heater then it should go directly after the UV with the heater outlet feeding into the Nexus.

Hi there .. thank you for your help .. my heater is on the out pipe directly off the filter .. was going to do the same with the nexus ..the return pipe is over the pond as a pipe spraying onto the surface via a water blade in the warmer months and 2 inch pvc during the colder months.. my filters are sutuated 1.5 metres above water level..

Do I understand that correctly? Are you returning by gravity from the output of a pump fed filter back to the pond but going through the heater?

Yes mate heater on the out pipe on a pump fed filter ..

Sent you an email with a pic mate if it helps .wouldnt let me post on here as it said the file was to big

I didn't get your email Lee, I'm not sure why, it may be that the address you sent it to was incorrect or the files size of the attachment was too large to send via this forum. I don't like putting email addresses on open forums so, if you PM me your email address, I'll send you an email directly from an address that will accept large attached files and then you can reply to that. That'll work.

I would have to say if running pump fed set ( pump in the pond then to the filter ) you need as few bends or restrictions on the return pipe work from the filter. and the return pipework should be 4 inch but you could get away with a 3 inch pipe if running a water pump under 6000lt per hour. having the heater or UV on the return pipe will slow the water returning to the pond and as the pond matures the pipe work gets a build up of crap on the inside making the flow even slower. it is always better having the return pipe as big as possible.

That was what I was thinking, Vince,

Putting the UV into pipework that's returning water to the pond by gravity will make a restriction to the flow rate.