I had seen the bio filters that look like closed barrels that sit outside the pond. That was what I first thought of getting but since its my Stocktank that is above ground, it would be difficult to set up and it still would need a pump. I think this that I just bought will work well, at least I hope so. I did not get to setting it up yesterday or this morning so will do so later.

I did pipe boot connections on my retrodrain through the wall of the pond. Didn't make my hole as large as what Horton suggested--only 1/2 the diameter of whatever size pipe. Most recent was 3" and made a 1 1/2" hole in the centre of where I wanted the pipe. The liner stretches but it takes strong fingers. Easy to do and as far as I know no leaks. Curious why aren't you looking at external pumps for your pond? They are more energy efficient, easy to winterize. I have a priming pot on both of mine even though they are below ground but had a problem with quilt batting getting wrapped around the impeller of the older pump before using a priming pot. I have a Sequel 4350GPH pump that is very quiet uses 175W. This year I plumbed this pump to my sc and the old pump (Sequence 750 4200GPH but only pumping about 1/2 of that due to bent shaft) to my skimmer. I probably don't need both pumps as also changed my waterfall out this year so is smaller. The Sequence is noisy and leaks a little on start up around the shaft. Long story short I love the external pumps. Aquaart carries good external pumps and also the bottom drain that is mentioned either here or other forums. I also like the skimmer--it collects alot of surface stuff like dust! In the fall I run my pond on the skimmer only so that I can remove my drains (have a midwater drain now which is also awesome) before the water gets too cold. Like Horton my pumps/sc are hidden under a deck. Two pummps might be an idea for your pond as you need less flow through your biofilter and more flow through your waterfall. One idea I saw here if you only use one pump and need the circulation (in your case at least 5000GPH) was to pump part of the water back into the main pond and the rest through the biofilter/stream. Aquaart has a diagram of how to do this. As for valves depends on if you have a drain on you skippy filter etc. I have a knife valve between pond and sc on the bd but on the midwater drain which also goes into sc I don''t--I use a standpipe. After skimmer and sc 2" ball valves--I know could have used knife valves there but ball valves are more reliable. My check valves are after the pump but before the ball valves to the waterfall filters. This is to keep the water from the waterfall filters coming back down through the pump and into the pond if power goes off which it does here frequently. Because I have priming pots, sc and skimmer I don't need check valve before the pump. Can't remember when you need check valve before the pump--sorry. Ball valves after the check valves to control flow to filters. I know that I could get away with running one pump now due to the changes I made in adding a midwater drain to my sc (had alot of draw down!) and waterfall changes as the valve on my Sequel pump to higher waterfall is turned down more than 1/3rd. It's just time consuming and more pipe to change it out again. I don't know if you are allowed to use ABS in the US. I use it here as fittings are available and it stands up to my climate. Also because it's black any pipework in the pond lie retro bd don't show as much. You have a fun project on your hands! It can get rather overwhelming but there are many knowledgable people on this forum who can help you. Good luck. Patti

hawkiefriend, What are you pumping to? Do you have a filter set up outside of your pond that you are pumping to or is the mesh bag and whatever is put in it, going to be the only means of filtration. If it is just a pre-filter requirement, then you don't really need anything inside the bag, as this is a mechanical filter. But you don't want the bag to collapse around the pump and possibly cause a plug up. Was this "bag" actually designed to be used as a pre-filter, or is it one of those laundry bags with the wire frame? If it is the only means of filtration, then filling the mesh bag with pot scrubbers, will do the job of providing surfaces for the bacteria to colonize. The "scrubbies" [nylon bun shaped type] will act as the bio-filter material,just pack them into the bag, as many as you can. Be sure you do not block the pump's intake with anything. A "scrubbie" placed in front of the intake, may plug up with gunk, but the "scrubbie" it's self, should not be sucked into the pump, unless it completely unravels, which is highly unlikely. All that a pre-filter is there for, is mechanical filtration, to stop hard objects, like pea gravel, bits of twigs, etc, from being sucked into the pump's impeller and doing damage. Hope this helps, "Horton"

I live in Utah, so have winters very similar to yours. My pond is 1,000 gal as well, with a depth ranging from 18-28 inches, and I keep the pump running through the streams and waterfalls 24/7 all year long. Last year we had 3 straight weeks where the temps were between 6-19 degrees. Never any higher. I keep an electric de-icer in front of the skimmer and that keeps the water moving. Additionally, the pump moves water at a pretty good rate - 4,500 gal/minute - so that helps. I've noticed during the past 2 winters that when it's really cold the water freezes for about 2 inches deep, and it's liquid below that. The ice freezes on top of the streams, like in the mountains, but the water moves freely under the ice. It's really very pretty. When we have the warmer breaks in the weather, as we invariably do in the mountain states, the ice melts and I disconnect the heater until the next cold spell. The fish have all survived beautifully each winter. I don't feed them; I do check on them to be sure everything is OK. When the temps are cold, they spend their winters lounging in their tunnels and I rarely see anything more than a peek of their tails and their noses. I have 3 tunnels for 15 fish that range in size from 14 inches down to 4 inches. The vast majority of them are 8 inches or less. Also, water does evaporate, even when it's cold and it has snowed. So I always monitor the water level of the pond and add more, when necessary. This amounts to usually once a month, I need to add water to bring it up to the max fill level. Also, once a month, I'll put on my waders and climb into the pond to pull out algae or leaves that have blown in. I like to keep debris and other vegetation (except the sunk aquatic plants that are over-wintering) out of the pond so the water stays clear and clean -- and it always is clear and clean. Hope this helps. We are lucky in that our mountain weather rarely stays cold for long periods of time. I think that makes it much easier on our ponds and their inhabitants.