Intake Bay vs. Wetland Filtration

[SeanSYW]

I was thinking of adding a short creek that might double as an intake bay for my pond. But was hoping for a good amount of added biofiltration. Does an intake bay provide similar functions in terms of filtration as a shallow wetland filter? If both have the water pass through gravel, what’s the difference other than infiltration vs upwelling of water?

Thanks!

 

[poconojoe]

I believe an intake bay acts more like a skimmer to draw any floating debris to it. I don't think it's much of a filter per se.

A wetland bog filter strains out any solids and the beneficial bacteria colony breaks that down. Plus, plants are grown in the gravel which help remove excess nutrients from the water. Much more happening here than with the intake bay.

Now I'm no expert on intake bays. Maybe under all that gravel there might be some beneficial bacteria living down there. Hopefully the experts will chime in.

 

[Lisak1]

I'd agree with that 100% @poconojoe . Wetland filtration is upflow, intake bay is downflow. And yes - I'm sure there are bacteria colonizing the gravel in an intake bay, but that's not it's primary purpose.

 

[GBBUDD]

I just altered my intake bay sorta speak as I'm not exactly sure what it is anymore. I have a negative edge that drops over a foot to a mini pond where my intake for my pump is in an aquablock. This was buried under 3 to 4 inch river rock. Here's tge issue I was having while tge debris is pulled to the intake area and it makes it way inbetween the rocks its impossible to easily pull out the debris. Well I am going to cut matala pads and encircle tge aquablock so I now have a way to remove a filter material of heaviest debris and not get churned up by tge pump. I still have plenty of debris from the main drain making its way to feed the bog.

 

[SeanSYW]

I'd agree with that 100% @poconojoe . Wetland filtration is upflow, intake bay is downflow. And yes - I'm sure there are bacteria colonizing the gravel in an intake bay, but that's not it's primary purpose.

Thanks both you and @poconojoe are very knowledgeable! I was planning on planting stuff in the gravel bed of the intake bay, cause I also love plants and they’d help with filtration. But at that point, with a decent layer of gravel and plants, I can’t think of the difference between the wetland and intake other than the direction of flow. Would that direction of flow make such a big difference in terms of biofiltration capacity? or maybe I shouldn’t have assumed plants can grow in an intake bay

 

[SeanSYW]

I just altered my intake bay sorta speak as I'm not exactly sure what it is anymore. I have a negative edge that drops over a foot to a mini pond where my intake for my pump is in an aquablock. This was buried under 3 to 4 inch river rock. Here's tge issue I was having while tge debris is pulled to the intake area and it makes it way inbetween the rocks its impossible to easily pull out the debris. Well I am going to cut matala pads and encircle tge aquablock so I now have a way to remove a filter material of heaviest debris and not get churned up by tge pump. I still have plenty of debris from the main drain making its way to feed the bog.

Would adding another mode of sediment size help? ie a fine grain pea gravel or smaller on top of the 4” river rock so there would be a smoother surface to pull out debris? I’d assume this would also increase filtration.

 

[GBBUDD]

Its not that i have an issue with anything getting through its more what is not and is stuck between the rocks where you cant clean. this way after a month i can just pull back the layer of rock and clean the filter that has the debris caught up in it. im talking the course pads

 

[Jhn]

Thanks both you and @poconojoe are very knowledgeable! I was planning on planting stuff in the gravel bed of the intake bay, cause I also love plants and they’d help with filtration. But at that point, with a decent layer of gravel and plants, I can’t think of the difference between the wetland and intake other than the direction of flow. Would that direction of flow make such a big difference in terms of biofiltration capacity? or maybe I shouldn’t have assumed plants can grow in an intake bay

As @poconojoe said the intake bay takes the place of a skimmer, it is going to be hard to clean debris out of there if you have plants growing in the intake bay, Which will eventually cause it to clog.

You will still get the gravel in the water of an intake bay being part of the biofilter, as any wet surface will be colonized by beneficial bacteria, that is where any similarity ends to a wetland filter, though. There is also dwell time in a wetland filter if the water is passing through the planted area quickly then the plants aren’t as effective at pulling out nutrients.
Intake bays can house multiple pumps, which are pulling a lot of water into the area, take mine for instance it has a 10,000 and 3000 gph pump in it. The 3000 gph pump feeds my wetland filter and the 10,000 gph one feeds a waterfall, that is a lot a flow through the rock and gravel,

 

[GBBUDD]

@Jhn any luck finding that spot in the bog ?

 

[Jhn]

@Jhn any luck finding that spot in the bog ?

Yep found it and had another leak in the pond, that I just found and patched. It was an exercise in patience letting the pond slowly drop, then finding the hole. Of all places the pinky size hole, was under a dinky 150lb. Rock, not under all the 1000lb. Or heavier rocks. Fortunately, I could just put the board back under the liner where I seamed them together, and keep the pond with fish in it separate. On the plus side the seam is holding fine in the older pond as it’s been underwater for a week now,

 

[GBBUDD]

@Jhn How much water do you replace in a day or a week ?

 

[Jhn]

@Jhn How much water do you replace in a day or a week ?

was losing a steady 2” a day once I separated the two ponds until it got to the level of the hole. Something must have been blocking/clogging the hole initially, the water in the pond wasn’t dropping initially or at least not enough that I noticed. Pond dropped to about 15” in the deep end then a little cove off to the side should have been holding a couple inches of water and it emptied itself overnight, so that was the first place I looked and sure enough there was the hole,

 

[GBBUDD]

@how much evaporation were you replacing before the expansion

 

[Jhn]

Not much, especially this time of year, It would take a week in the hot part of summer to lose and inch or two. Granted not as much large rock and non woven cloth over the liner like there is in the addition so will probably be a little more evap Loss.

 

[Lisak1]

You could plant an intake bay... HOWEVER you'd need to be very careful to watch root growth to make sure you weren't blocking water flow. Also as @GBBUDD is finding, you're skimming debris, which you need an easy way to clean. I also have a negative edge - not a true intake bay - and have to clean the gravel from time to time. Not a hard job, but you do want to be able to get in there and rake and spray things down just to keep it moving. And remember any down flow will be affected by debris build up. An up flow bog won't as it has pushing power of water behind it.