Filtration rate vs. circulation rate. Let's hash this one out.

[combatwombat]

I'm about to buy the pump(s) for my water garden / fish pond (not a koi pond!) and want to at least get some opinions about whether or not I'm on the right track.

Most general advice you can find online says you want to "turnover" your water anywhere from every 30 min for smaller ponds to 2 hours for bigger ponds and even less frequency is required for huge ponds. Of course, "small", "bigger" and "huge" are subjective terms...

I estimate my pond will be about 7,000 gallons after all the rocks are in. I will filter with an upflow wetland filter / gravel bog exclusively.

For most ecosystem ponds, turnover rate, circulation rate, and filtration rate are synonymous. 100% of your water turnover is pumped from your pond to your biological filter. You're filtering and circulating the same amount of water at all times.

Now, my bog surface area will be about 15% of my pond surface area as well as by volume (about 1000 gallon filter size).

A bog/wetland filter, as far as I've read on here, can probably do okay regardless how much flow you throw at it, but it's better to increase dwell time if possible. Slower flow = better filtering as I understand it.

If I shoot for a 30 minute dwell time in the bog, that would require a 2,000 gal/hour pump.

I have a feeling that if I told you, "I plan to power my 7,000 gal pond with a 2,000 gal/hr pump, I'd get some funny looks from everyone here.

So that's where I'm left wondering, how do those of you with bogs think about "turnover" in your pond.

Would it be a wild idea to use a 2,000 gal/hr pump on the wetland filter and then a bigger pump to run some jets or another waterfall, unfiltered, to make sure I'm still circulating the whole pond once every 60-90 minutes or so?

 

[brokensword]

I'll just tell you how I do it and you can judge for yourself; I have (2) 4200 gph pumps. Each has a Y which feeds one waterfall and one bog inlet. I don't have actual numbers re how much gallons go where because I valve off based on what I want from my waterfall flows. I'd guess though that it's nearly half, maybe a bit more for the waterfall. So, my pond is 7K gallons and I have 8.4K gph total. Since head has to be taken into account, your output to your bog/wfall may vary.

My bog is approx 24 x 3 x 3. The outpour is over a stacked rock wall and there are some 'falls' but mostly a slower flow over the entilre length. It's not a trickle so 'slow' isn't probably an apt term for how fast my water flows in the bog but since I have 3' depth, there's a lot more time inside the gravel/stone.

If you put valves and Ts/Ys on all your outputs/inputs, you can deliver water wherever and whenever/however you want.

I have video on the Pic subforum if you want to see how my bog and it's flow is working.

 

[combatwombat]

Thanks, @brokensword. Your pond sounds like a great baseline for me to use on mine since we'll be about the same volume. Is your bog your only filtration? If so, sounds like you're filtering your water a little more than once every 2 hours and circulating it about every hour.

How happy are you with water quality / visibility? I would expect I'll have a much lighter fish load than you, so if you're happy with it, I figure I'll be very happy if I do something similar.

 

[Jhn]

Yes, would run another stronger pump to a waterfall....lts what I do, running a 3000 gph pump to a 12x12 x3’ deep bog, and a 10,000gph pump to a waterfall on a 10,000 gallon pond.

You would probably get away with just the one 2000gph pump for awhile until your fish overpopulate the pond, then issues would probably eventually start popping up.

 

[brokensword]

Thanks, @brokensword. Your pond sounds like a great baseline for me to use on mine since we'll be about the same volume. Is your bog your only filtration? If so, sounds like you're filtering your water a little more than once every 2 hours and circulating it about every hour.

How happy are you with water quality / visibility? I would expect I'll have a much lighter fish load than you, so if you're happy with it, I figure I'll be very happy if I do something similar.

Yes, the bog is my filtration. Check out the vids; the clarity is more than fine as the camera points toward the far side at about 14'. My koi are still smaller so time will tell if I have to run more water through the bog but I doubt it as even the gravel layering the bottom becomes a bacteria colony. And having a lot of plants deters the algae blooms others routinely get.

http://swordofshakespeare.com/Sword_of_Shakespeare/pond_2020_p2_files/200919 - pondcam.m4v

 

[GBBUDD]

I am beyond a firm believer in over filtration. Meaning 15 percent is low id double or come close to doubling it . Your maintenance will be that much less and your issues resolved much faster say If a fish that dies and you have no idea where it is .
U know 2000 gph sounds like a lot of water but its really not unfortunately heres a video to help you see whats what

 

[addy1]

I turn over the water about every two hours, maybe, large bog only filtration no koi. Zero issues with water quality. One pump for the 5 ponds and the bog. The deck ponds and stream ponds are run by a clear water pump that runs on a timer. It handles the 100 plus foot head pressure. Those ponds are not filtered, except by plants in them, they send dirty water down to the big pond system.

I am too cheap to run pumps that are not needed. Don't even notice a bump in the electric bill when I turn it on in the spring
Again zero koi, just a lot of shubunkins.

 

[Lisak1]

We use an Aquascape variable pump - 4000 to 8000 GPH- and run it at the very lowest speed most of the time. We put probably 80% of the water through the bog and the rest through a small stream. We can shift water from bog to stream with ball valves, so we do play around with it a bit. I watch the bog to see how fast water is percolating out of it and try to keep it so you can just see water movement at the surface. As the plants grow we may push a bit more through the bog or up the pump speed to get the water flow we like over the waterfall. So you can see - we are completely unscientific about the whole thing!

Our total system is around 4000 gallons of water and I would guess we're running the pump well under 5000GPH most of the time.

 

[GBBUDD]

Don't even notice

Your not in CT thats for sure its gotten so bad here a 75 watt bulb is noticeable

 

[combatwombat]

@GBBUDD: I would make it 1000x bigger if I could. I don't have the space for it, so 15% is what it's gotta be and I'll live with it. I know 2k gph will be a puny waterfall, but I can also use a bigger pump, tee off of it before the bog and dump the rest of it on top to make the waterfall bigger.

@addy1: I love your approach to ponding. I wish I were as relaxed about it as you! I will probably start with less flow and, if necessary, upgrade if I run into problems.

@Lisak1: Thanks for the data point.

I'm kind of attracted to the idea of using the smallest line voltage pump I can get away with to do filtration and supply the waterfall, and then make up the rest with some low voltage circulation pumps.

 

[GBBUDD]

Keep the fish load low . the maintenance up keep high and you could be fine . i do not have a light fish load i am not good about daily maintenance. as i often leave the pond for weeks on end.

 

[GBBUDD]

I don't have the space for it, so 15% is what it's gotta be

like addy1 she made hers double the depth and it has worked well for her.

 

[addy1]

@addy1: I love your approach to ponding. I wish I were as relaxed about it as you! I will probably start with less flow and, if necessary, upgrade if I run into problems.

I am a somewhat lazy ponder, did not want anything I could not walk away from without worry. I can turn the pond on and basically ignore it for the summer. The only thing I do need to watch is the plant growth in the bog.

Never wanted to "waste" money, the pump I am using I brought from my pond in AZ. Even there with the horrible electric rates it never showed up on the bill, when we first started using it. There it ran 24/7/365 days. I spent the money on a good one that had decent flow and low power use. A dragon lim pump. http://www.wlimstore.com/pumps/dragon.php

The stream is different. It needs watching, 85 feet long, plants like to grow in it and the deer walk in it. That I keep a eye on. I have a good neighbor I can call if I see issues. A clear water pump on a timer.

I do not have koi that also makes it easy to have a lazy pond outlook.

My bog is 2.5 feet deep. Lots of filtration.

 

[Stephen Noble]

Turnover Rate is sometimes erroneously described as gallons per hour (GPH). One might reasonably think that if a pump rated at 2000 GPH is placed in service on a 200-gallon pond all of the water will pass through the filter ten times in one hour. This is not true. Some of the filtered water will be immediately re-filtered while some dirty water will remain unfiltered for an “X” amount of time. So how does the hobbyist take turnover rate into account? Short of solving mathematical equations, try to provide maximum flow through filtration. Gallons per hour (sometimes called flow rate) is the number of gallons pumping at zero head height, with no restrictions (plumbing & filters), in one hour.

 

[combatwombat]

@Stephen Noble: I supposed jets and other things to help circulation would help reduce that "x amount of time." Pulling water from different areas of your pond into your intake would help too, I guess.