Go Back   Practical Fishkeeping Forum » POND FORUM » Ponds » Pond Equipment

Reply
 
Thread Tools
Old 20th May 2008, 08:10   #1
dawdle
 
Join Date: Apr 2008
Posts: 78
dawdle has disabled reputation
Default Bio filter flow rates?

One of the changes I made to our pond that was ok and now is not was to change the pipe from the pump to filter as it was clear pvc and would get blocked with blanketweed. This did increase the flow rate through the filter quite a lot.

I checked the flow rate through our filter yesterday and it is 800lph. In our 450l pond that means the pump turns the pond over 42.5 times a day.

I messed around with the flow rate and after leaving it at 450lph for an hour or so I saw a big difference in the nitrate(Edit: Keep doing that should be nitrite.) level from the filter vs the pond. But at about half the flow it should be doing double the work? It's impossible for me to calculate if it would be more efficient at that rate as my tests are not accurate enough.

I realise there are so many variables but wondered if anyone had any experience with flow rates through filters and whether flow rates can make a difference to efficiency.

Thanks.

Last edited by dawdle; 20th May 2008 at 16:01.
dawdle is offline   Reply With Quote
Old 20th May 2008, 11:47   #2
jpcwebb
 
jpcwebb's Avatar
 
Join Date: May 2007
Location: Reading, Berkshire
Posts: 343
jpcwebb has proved to be helpful.
Default

Residency in the filter is one aspect, but filter media surface area is also a big factor - you can get away with higher flow rates if you have the right kind of filter media (ideally with very high surface area), and the filter chamber is big enough. Temperature also plays a big part, so efficiency will vary from season to season and on a diurnal basis (night vs day) and depending on the weather. Also, you want to strike a balance between increased retention time in the filter and adequate turn over of the pond to process the waste and keep the water moving. The general rule of thumb is turn over the volume of the pond between 8 and 12 times a day. But as you say, there are so many variables that I think it really comes down to trial and error. I think you could nevertheless reduce it further (maybe split the flow from the pump to reduce strain on it). In the winter you may want to reduce it to a trickle otherwise you risk excessively chilling the water and losing the thermal stratification.

Last edited by jpcwebb; 20th May 2008 at 11:50.
jpcwebb is offline   Reply With Quote
Reply

Bookmarks

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Jump to another section


All times are GMT. The time now is 09:06.