Rethinking My Wayterfall/Stream. Several Questions

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Firstly, I appreciate all the help that has been provided to date.

My pond is app. 6,400 gallons and average depth of say 3 feet.

Originally I decided to add a nice 3 foot waterfall with a 4 foot wide and 30 foot long stream.

As I now realize a single 3 foot drop has splash issues I had not considered (thank you for the heads up, GBBUDD) I decided to go with a series of smaller drops to minimize splash and add interest.

As I am now obsessed with my new hobby I started reading more on the forum before picking up the shovel again.

I started to read about bog filters (elevated ,gravel upflow) and thought why not. In for a penny in for a pound.

Initial thought was place the bog ( in a plastic stock tank behind the waterfall but at same or slightly higher level to aid flow to spillway from stock tank. Am I correct that bog outflow cannot be lower than spillway or I will have possible bog overflow due to pressure?

If this is the case I may scrape the waterfall and just go with a nice stream or possibly a lower waterfall as elevating the bog to 3 feet on a foundation of compacted earth may look silly and present difficulties in accessing the bog for planting etc.

So I researched the heck out of bog filters planned out the plumbing (1.5 or 2 in pvc with slots in top every 4-6 inches, cap the ends and of course a clean out pipe just above gravel which would be capped. I would be using an 8 foot diameter 2 foot high stock tank with a drain plug. The bog itself would be no more than re recommended 12 inches deep. And I would use 3/8 pea gravel as a bed.

Of course I then read about dwell time which frankly makes little sense to me. I see dwell time in minutes which would necessitate a slow flow in the order perhaps hundreds as opposed to thousands of gallons an hour. My pump flow with calculated head pressure would be app. 3,000 GPH.

So now I'm thinking too fast for a bog so lets do the following, place the bog next to the waterfall and add a Y connector with ball valves. Now most of flow to waterfall and minimal flow to bog and let this "trickle" from the bog enter the pond directly. Of course if I go this route most of my water is not being filtered by the bog but rather feeding the waterfall !! So what was the point of building a bog?

So now really lost. As I understand it the beneficial bacteria only need contact time of seconds to convert products so not really sure where this dwell time of 6-8 minutes came from. Maybe I'm wrong but I would think greater flow is greater turnover which equates to better filtration.

Iwould bet there are upflow bogs with fast and with slow flow and possibly they both work.

FWIW: I currently have no filtration. None, nada. And believe it or not I can see the bottom of my pond ! Thank you, Mother Nature.

Look I do realize the bog would aid in the health of my pond but I can clearly do without it. I do not have KOI. Just a half dozen pet shop goldfish, some frogs,cattails and lots of water hyacinth (geat for filtering as I understand it.) I am in full sun and never had an issue with algae. Maybe I am just lucky. I live in north central Florida (Ocala) so I have more than my share of hot days and blistering sun but no algae. Go figure.

OK too long winded. Just need opinions on whether to have water flow from bog to waterfall at high flow rate or put in a Y connector and have bog flow SLOOOOW. Must outflow of bog be higher than the top of my waterfall ??

Also, do I NEED a clean out pipe if I do a bog. Couldn't I simply shut off the pump ( I will install a check valve to prevent dirty water from back flowing to pond) open the drain valve on the stock tank and let the muck drain out?)

Lastly, since koi are as I understand it are a form of carp which typically live in muddy water several feet deep why do koi afficianados ( and I respect their hobby) strive for crystal clear water? Is it a pride thing or just to better visualize the fish because honestly in my pond with NO current filtration I could for sure see koi if I were to stock them.

I appreciate all your past and future advice.
 
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JRS

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Congrats, sounds like you have a very well balanced natural pond.

Some of the benefit of a bog besides ammonia cycle filtration is a settling chamber for fine debris. The plants will then use this as nutrients. You do not need a clean out, many folks here mention having them but never needing them, especially with your stock tank drain.

You do not have to run all your water through the bog, especially with the balance you have. I only a run a portion through my small cattail bog and it was enough to solve the greenwater problem on my network of turtle tubs and in ground pond.

If I understand correctly, you would want your stock tank higher than your waterfall to prevent the backflow.
 
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Congrats, sounds like you have a very well balanced natural pond.

Some of the benefit of a bog besides ammonia cycle filtration is a settling chamber for fine debris. The plants will then use this as nutrients. You do not need a clean out, many folks here mention having them but never needing them, especially with your stock tank drain.

You do not have to run all your water through the bog, especially with the balance you have. I only a run a portion through my small cattail bog and it was enough to solve the greenwater problem on my network of turtle tubs and in ground pond.

If I understand correctly, you would want your stock tank higher than your waterfall to prevent the backflow.
I appreciate your input.
Pics to follow if I get this done
 
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A good resource for bogs is the sticky thread on bog building in this forum, which you may have already looked at, it is lengthy though so it takes time to go through it. Honestly I would not dwell on "dwell time" lol. Not sure where that came from. It would be pretty tough to calculate that accurately. I think people do not talk about that too much because generally you size your bog to the size of your pond, you probably mentioned in another thread the size of your pond. Usually it is recommended that your bog is about 30% the size of your pond, square footage wise. Can be less than that if you do not have a large fish load. Dwell time does come into play because you do want time for the bacteria to do its magic but I dont think you see people talk about because if you size your bog correctly then that basically takes care of itself. As you mention you can get control the flow with a ball valve and it is great if you can put a wye fitting, have one pipe to deliver to the manifold and the other to the top of the bog. That way you can control the flow through the bog, plus control the stream/waterfall flow.
As for why some want crystal clear water, that is the great divide between this forum and other koi forums. Here we are happy with nature doing its thing with minimal maintenance. Other forums are more about having pristine water for their koi, not knocking them, some people invest a lot of money in koi and get concerned about diseases or the water making the fish sick, so they invest a lot into mechanical filtration. I am not trying to get into that debate, just pointing the different viewpoints.
I will say the bog does a great job of keeping the water clear, I have only had my pond running since September and it is pretty amazing how quickly it clears things up.
 
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A good resource for bogs is the sticky thread on bog building in this forum, which you may have already looked at, it is lengthy though so it takes time to go through it. Honestly I would not dwell on "dwell time" lol. Not sure where that came from. It would be pretty tough to calculate that accurately. I think people do not talk about that too much because generally you size your bog to the size of your pond, you probably mentioned in another thread the size of your pond. Usually it is recommended that your bog is about 30% the size of your pond, square footage wise. Can be less than that if you do not have a large fish load. Dwell time does come into play because you do want time for the bacteria to do its magic but I dont think you see people talk about because if you size your bog correctly then that basically takes care of itself. As you mention you can get control the flow with a ball valve and it is great if you can put a wye fitting, have one pipe to deliver to the manifold and the other to the top of the bog. That way you can control the flow through the bog, plus control the stream/waterfall flow.
As for why some want crystal clear water, that is the great divide between this forum and other koi forums. Here we are happy with nature doing its thing with minimal maintenance. Other forums are more about having pristine water for their koi, not knocking them, some people invest a lot of money in koi and get concerned about diseases or the water making the fish sick, so they invest a lot into mechanical filtration. I am not trying to get into that debate, just pointing the different viewpoints.
I will say the bog does a great job of keeping the water clear, I have only had my pond running since September and it is pretty amazing how quickly it clears things up.
Yeah, I will not dwell on dwell any more.

Time to pick up the shovel

Appreciate your response
 
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It's a good distinction @Pablo and one that many new pond owners don't always understand. A dedicated koi pond and an eco-system pond are different in a number of ways.
 

YShahar

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One trick to slowing the water down enough to give the bacteria time to do their thing is to create a void space underneath your layer of gravel. The pros do it with Aquablocks, but much more affordable to use milk crates. Check out @combatwombat's build for how he used milk crates in his bog and intake bay.

You can also size up your delivery pipe by using a large-diameter drainage pipe underneath the milk crates. This is the same idea as the Aquascape centipede (but a good bit cheaper!). Another such pipe makes a good clean-out pipe, but of course, if your stock tank has a drain, you could clean out any built-up muck by just draining it into the garden.
 

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