Simply Koi and More Koi

i have a problem i have a 6000 litre pump and my pond is just over that 1500 gallons i am turning the water over every hour but
i am pushing the water through a luguna filterfalls i have ramed as much media as i can extra mating boi balls ect there is pleanty of little grubs in the filfetr little wormy things ect eating the crap and there will be more i am sure as filter been running 4 weeks so looking good there but i have been told i am pushing two much water through it
so can i from the pump pass my two uv lights then split the water as i have got a HOZELOCK BIOFORCE 9000 none uv filter
i have a y spiltter from laguna with the fast fit tails so can send to both this will slow the water down in main filter i am running 1 and quarter pipe and the y splitter can be cut to what size i want so can send 1 and qurter ince pipe to main filter and smaller to the other or do i just split even and slow the water to both
i was told the water should take about 20 mins to pass through a filter ?
any help please

but i have been told i am pushing two much water through it

By.....?

i was told the water should take about 20 mins to pass through a filter ?

Depends how big the filter is.There's no single easy answer to how long water should be in a filter.

But in your case the filter should have a maximum design rate in gallons per hour.If you are exceeding that then splitting the feed to two filters will help.Whether it's what you need is another question altogether.

i have a 6000 litre pump and my pond is just over that 1500 gallons i am turning the water over every hour

If you are pumping to any height (say two feet above water level),and if the run is long (say 15 feet of pipe) and you're using 1 1/4 inch pipe,then you won't be shifting 6,000 lph.More like 4,500 max.The only way to check is to measure the output of the filter.My 2,700 gph pump gives around 2,000 gph @ 900mm head using two inch pipe.