planning water course, placement of bog filter pools & waterfall relative to each other. also minimum bog filter pool depth Q


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Hello!

I searched but wasn't having luck finding info. I'm in the planning stages for a first small above ground water garden using a rubbermaid stock tank and a couple preformed header pools and waterfall spillway (I want to get it set up first and then worry about dressing up the fascade later over time, as I have three goldfish in desperate need of larger quarters than their current 40 gal aquarium; below ground not an option at this time). The main pond will be 300 gallons, oval and about 30 sq ft surface area. Of the two forms for the bogs, one is relatively shallow (8 inches deep) and the other is 2 ft deep, together they have a surface area 30% of the main pond. I also have a waterfall spillway with an 8 inch weir. Space is an issue for me so I envision the water course taking a tighter U shape so that the two bogs run along the longer side of the oval to make a U shape

1) In setting things up, do I need to split the flow from the pump and have part go to the bog pools that will gravity feed into the main pond and then a waterfall at the opposite end of the pond, or is there some way to have a waterfall feed into the bog filter pools? Also will the bog filters be effective if they are both top filled or is it really crucial that the deeper one bottom fill?

2) I am assuming that the very shallow preform can be used as secondary bog filter to the deeper one with shallow rooting marginal plants (eg, I've seen watercress growing in local shallow streams only an inch or two deep), but is this true? I live in zone 10a if choice of plants is an issue

3) I'd like to have submerged plants carpeting the bottom of the main pond so I can transfer my bamboo shrimp and snails over (none of my species can reproduce in pond conditions and they'd have to walk almost a quarter mile over asphalt to find a wildlife water source so no worries about invasive species issues), they already get along fine with my fish and I'd like to have the extra help with algae and scum mgmt. So I would actually want to start with a substrate, but I've seen many here say no to any substrate. Thoughts?

4) I'm planning to start my plants in a smaller water garden container as I get the real water garden set up over time to get the plants bigger and established due to one of the goldfish being a bit rough on tiny aquarium sized plants, is this generally a good idea or would transferring them from a location with potentially differing amount of light or warmer water temp due to smaller container just muck things up?

Any thoughts or pointers or "this is a bad idea" are welcome, I'd like to build it once and have it right! Thank you!
 
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brokensword

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1) In setting things up, do I need to split the flow from the pump and have part go to the bog pools that will gravity feed into the main pond and then a waterfall at the opposite end of the pond, or is there some way to have a waterfall feed into the bog filter pools? Also will the bog filters be effective if they are both top filled or is it really crucial that the deeper one bottom fill?
You can feed from the waterfall to your bogs but it gets more complicated than it has to (imo) and isn't worth it. I'd go with the split line into both endpoints. Use valves so you can control each feed. Btw, a bog (upflow wetland filter) works best by sending the water to the bog's bottom and letting it rise up through the gravel and where the plant roots can do their thing. Fed from the top you quickly get a buildup and the water merely pours over, eliminating much of the bog's function relative to a pond filter. Natural bogs are large, very wide spaces and the water has to travel more, giving that type a chance to filter out organics and such before reaching the main waterway. A backyard pond needs a deeper upflow function.

2) I am assuming that the very shallow preform can be used as secondary bog filter to the deeper one with shallow rooting marginal plants (eg, I've seen watercress growing in local shallow streams only an inch or two deep), but is this true? I live in zone 10a if choice of plants is an issue
sure, no problem. As your watercress thrives, thin it out every now and then as it is the aggressive growth that fuels better filtration.

3) I'd like to have submerged plants carpeting the bottom of the main pond so I can transfer my bamboo shrimp and snails over (none of my species can reproduce in pond conditions and they'd have to walk almost a quarter mile over asphalt to find a wildlife water source so no worries about invasive species issues), they already get along fine with my fish and I'd like to have the extra help with algae and scum mgmt. So I would actually want to start with a substrate, but I've seen many here say no to any substrate. Thoughts?
Be careful as submerged plants give off O2 during the day but take it up at night. I'd keep the pond at 1/3 or so of your bottom surface. And the smaller the container (like yours) the more crucial this is going to be that you provide a lot of aeration and/or limit your fish stock. You will get variation of preferences re rock/gravel on the bottom or not. I like a thin layer of pea gravel for the koi to mess with as that is in their nature. The problems arise if you have to clean the bottom and it gets difficult when you have a lot of rock.

4) I'm planning to start my plants in a smaller water garden container as I get the real water garden set up over time to get the plants bigger and established due to one of the goldfish being a bit rough on tiny aquarium sized plants, is this generally a good idea or would transferring them from a location with potentially differing amount of light or warmer water temp due to smaller container just muck things up?

Any thoughts or pointers or "this is a bad idea" are welcome, I'd like to build it once and have it right! Thank you!
Good idea; I overwinter water lettuce for the same reason. If you have a good supply, the fish can't wipe out your plant herd . As the summer goes, I begin to compost the overly aggressive plants to keep my surface covered only at 60%. Re transfer; I'd have them adjust to very much colder water or, wait until the pond temp matches your smaller water garden container's temp. Some plants can be ornery if shocked too quickly and they'll stumble to thrive again when the temp warms. For my more tropical overwintered plants, I usually wait until June here in Mi for the water temp to be at least 65. And if you're bringing your plants from inside to outside, harden them off for a week before tossing them into your pond.

Hope this helps!
 
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You can feed from the waterfall to your bogs but it gets more complicated than it has to (imo) and isn't worth it. I'd go with the split line into both endpoints. Use valves so you can control each feed. Btw, a bog (upflow wetland filter) works best by sending the water to the bog's bottom and letting it rise up through the gravel and where the plant roots can do their thing. Fed from the top you quickly get a buildup and the water merely pours over, eliminating much of the bog's function relative to a pond filter. Natural bogs are large, very wide spaces and the water has to travel more, giving that type a chance to filter out organics and such before reaching the main waterway. A backyard pond needs a deeper upflow function.
Thank you so much for your feedback. Given that the envisioned watercress bog would be both wide and shallow (I like to eat watercress, so no issues with thinning ;) ), do you think it would be okay to have water spilling into it from above from the deeper bog filter instead of flowing up from below for that one? Otherwise it seems like I'd have to use multiple splitters and each small bog would have to feed separately into the main pond?
 
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I guess your intention is to have one bog flow into the other.
I don't think that will work so good.
Pouring water over the top of the gravel in the second bog would not be a great idea as member brokensword has explained.

Separate the bogs and have each one spill directly into the pond.
You can do this by either using two pumps or one pump with a wye fitting on it's output. Do what brokensword suggested, have two valves after the wye fitting. This way you can adjust the flow to each.
If you have a third feature, like a waterfall, you might need an additional pump, unless your pump has enough output to serve all three, but I would think it would need to be pretty powerful to do that. In that case, add another wye and valve so one pump serves all three.
 

brokensword

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Yep, what Poconojoe said; let each fall back separately. I tried to 'gravity feed' my bog (which is your idea re bog one pouring into bog 2) and didn't like that I didn't have enough force. This is supposing you could get bog 1 to pour into a pipe/tube in bog 2, NOT as you're proposing. Bog filtration needs the force of the pump to help the magic happen. Water flowing overtop isn't going to do much after a very short time.

And I tend to recommend multiple pumps anyhow just for redundancy; you don't want to have your pond without a pump for very long waiting for a replacement.
 
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I guess your intention is to have one bog flow into the other.
I don't think that will work so good.
Pouring water over the top of the gravel in the second bog would not be a great idea as member brokensword has explained.

Separate the bogs and have each one spill directly into the pond.
You can do this by either using two pumps or one pump with a wye fitting on it's output. Do what brokensword suggested, have two valves after the wye fitting. This way you can adjust the flow to each.
If you have a third feature, like a waterfall, you might need an additional pump, unless your pump has enough output to serve all three, but I would think it would need to be pretty powerful to do that. In that case, add another wye and valve so one pump serves all three.

Thanks for your advice. In that case, I think I'll let one of the bogs act as a trickle waterfall feature and scrap having a separate waterfall. It's such a small main pond that having water flowing into it from three separate locations seems like it would mean there would be little room for any plants that prefer stiller water surfaces and it's harder to see through rippling water.
 
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welcome to the forum

As soon as plastic tubs get mentioned it is outside my experience and i see as a ticking time bomb . As the sharks say I'm out
 
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Welcome @Criscar ! Lots of great advice here, so I'll just add my welcome! Share some photos along the way and you'll get lots of helpful advice... better now than later when the build is done!
 
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addy1

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Welcome to our forum!

Lots of good advice up there. I had a top fed bog one time, small, it constantly clogged on top and overflowed.
 

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