TURNOVER RATE vs SETTLEMENT & CONTACT TIME

[Akinosan]

Hey Guys,
There are alot of great opinions about filtration on my new pond, and by the way, Jeff Duncal did express his concerns to me about this, but whats more important?, turnover rate, or the time your water has to move through your settlment chamber and contact time with your biofiltration media? I know they are both very important, but which would you choose?

[dick benbow]

used to be a time when it was all about dwell time. modern thinking now has turned the corner and is focused on turnover.

[GazKoi]

I would think that it is dependent on what type of filtration you are using.

If you was using a shower full of BHM then my understanding would be a very fast turnover rate seems to do the trick.

If you was using a more conventional type of filtration then you would not want to pump too fast as you would stand a chance of

1. Settlement not doing the job and ending up with a filter full of poop.

2. Not enough contact time with the bio and so the good guys cant do there work efficiently.

This is only my opinion as i have not really been keeping koi/water long enough but i am sure some of the very knowledgeable guys on here will help and correct me.....most probably

[JasonS]

Settlement wants the water gravity fed and moving as slowly as possible to allow everything to settle out. Biofiltration tends to want fast turnover, reducing the 'ambiant' ammonia/nitrite amounts. Ambiant ammonia amounts are the primary reason for lower PH too, IMHO.

So, for your 16x20 pond you want 4 (yes, FOUR) bottom drains going into 4 (yes, FOUR) 6ft (or bigger) vortexes then you can push to bead filters or showers or whatever. (Not going to get into the biofiltration argument yet) The main reason for 4 drains is the roughly 3000gph you can rely on from a 4" gravity fed pipe. Want turnover for the pond to be about once an hour during high season, can use less electricity when not feeding in winter.

OR you could put all those bottom drains into a single large, long, settlement that is also poured along with the pond. Put lots of brushes into the second half of that. Could even put jmat/matala/etc. into the pre-pump chamber.

OR could use microscreen(s) and smaller vortexes. W.Lim has a nice system that shouldn't break the bank in electricity or up front costs.