Quote:
Originally Posted by
andrewn15 
You are way over stock on koi population. How do you clean the filter with all of those lava rock?
I start out with 250 gal container of lava rock as my biofilter but then it crashed one day and most of my koi had problem, it was impossible to keep the muck out of that filter no matter how often I clean it, I ended up convert the container into a moving bed filter with K1 media.
Do you have a SC before the pump?
I'm also using the ultima II with sequence 1/4 hp pump but mainly for mechanical purpose, it draws clean water from the 150 gal vortex, feeds the ultima II then the moving bed filter, with daily small water change (backwash and dumping the vortex) the koi are doing great. My pond is close to 5000 gal and only have 6 koi 9-20".
Adrew