Plus 1 on the Koi style filter.
If it was me i would go with a set up as below.
have a concave bottom going into a bottom drain.
Feed this into a large settling tank with a dump valve so you can just open it up and drain off the rubbish at the bottom.
Next have a second tank or barrels filled with media, add a drain line to these so you can repeat the same process as with the settling tank.
At the bottom of each tank have a large airstone. With this you can throw a valve and the media / gunk will be stirred up ready to be drained off.
With this much volume you would be best aiming for 50% or more turn over to save money. Run a few large airstones in the pond to keep the water turned over.
Heating wise if required, investing in a boiler heating system would save you in the long run and a drip system would also be a good investment if water is safe/free.
Hope that all makes sense.
If it was me i would go with a set up as below.
have a concave bottom going into a bottom drain.
Feed this into a large settling tank with a dump valve so you can just open it up and drain off the rubbish at the bottom.
Next have a second tank or barrels filled with media, add a drain line to these so you can repeat the same process as with the settling tank.
At the bottom of each tank have a large airstone. With this you can throw a valve and the media / gunk will be stirred up ready to be drained off.
With this much volume you would be best aiming for 50% or more turn over to save money. Run a few large airstones in the pond to keep the water turned over.
Heating wise if required, investing in a boiler heating system would save you in the long run and a drip system would also be a good investment if water is safe/free.
Hope that all makes sense.
