Converting a pool to a pond: what can we reuse/bog plan critique.

[wamil]

I am planning to build a bog to convert an old pool into a pond.
I've never done anything like this before, so sorry if I'm a bit ignorant.
As for the goal, I'm not expecting perfect water clarity, but I want the water to be 'healthy' enough for aquatic plants and a few accompanying fish + an occasional swim.

Here are some pictures of the pool currently:

The pool is ~6' on the deep side and ~3' on the shallow side.

The current 'infrastructure' in the building next to the pool (pump, piping, filter):

I'm planning on removing the deck in the back of the pool yard and digging out a space there for the bog.
Here's a rough concept drawing of what I'm planning, but I'm open to changes if necessary.

I've read the post here: https://www.gardenpondforum.com/threads/bog-building.6894/, and I intend to follow it as a rough guide.

Since there is a layer of concrete coping surrounding the pool, I'm planning on having the bog's water flow over it back into the pool. It's different from the guide, but will this work okay?

Before I go out and start buying a pump/piping/pond liner/etc, I'm wondering if I can use any of the existing pool's plumbing.
I figure the solar water heater and the current filter will have to go, but can I at least use the existing underground~1.5-2" pipes and pump?
Now, they go from drain->filter/heater->pool, but I'm planning on changing them to drain->bottom of bog.
If necessary, I could get an entirely new external pump and intake, but I'd rather use the drain we already have if possible.

I'm very new to all of this so critique/suggestions are appreciated, nothing is set in stone. I still haven't figured out exactly what I'll need to buy as far as piping/pond liner/and pump (and more).

I'm in Carmel Valley, CA which is listed as 10a, but we regularly get a good few days of frost each year, so I'd estimate it at ~9a.
This will probably depend on what the bog and pool ends up like, but what kind of plants and fish should I look at? I want the pond to be a nice space for local flora and fauna, but some water lilies and/or lotuses and other ornamental or edible plants would be nice. We have lots of birds here, so I also plan to put some hiding spaces for any fish in the pool.

 

[wamil]

I'm sure there's a bunch of info I forgot to include, so please ask if anything is unclear.

 

[addy1]

Welcome to forum!

There have been some that have converted pools to ponds on here, might be able to find the threads with a search.

I would swap out the pump, get a more efficient pond pump. I don't see any reason you can't use the original pvc lines .
The pool filer won't do well with a pond. If you build a good bog filter you won't need a filter. I don't use any filer except the bog.

The bog water could flow over the coping back into the pond, I don't see why not

I am sure others will chime in and have other opinions.

 

[addy1]

Here is a list from a search

Search results for query: pool conversion

www.gardenpondforum.com

 

[Lisak1]

Welcome! You already have a beautiful setting, so you're on your way.

Search YouTube for "pool to pond conversion" if you haven't already - lots of good information there! I have no clue about pool plumbing, but I'm sure you can find great information on some of these videos.

 

[combatwombat]

Seen it done a few times, but haven’t paid a lot of attention to those builds. A few thoughts:

1. what size is plumbing? You can re-use it, but might be too small to service whole pond. You’re going to be flowing a lot more water than typical for a pool. For a single plumbing circuit on a pond your size, you’d probably need 3” lines. Maybe keep existing for circulation and add a circuit for new filtration?

2. Pool pump won’t do too well in pond application. Check it’s power consumption and compare to an efficient pond pump.Being in Cali and your energy prices, you’ll probably want the pond pump.

3. Bog is good enough for complete filtration if sized properly, but I’d hang onto the pool filter (sand filter?) and use it as a fines filter if water gets cloudy.

 

[j.w]

@wamil

 

[wamil]

Seen it done a few times, but haven’t paid a lot of attention to those builds. A few thoughts:

1. what size is plumbing? You can re-use it, but might be too small to service whole pond. You’re going to be flowing a lot more water than typical for a pool. For a single plumbing circuit on a pond your size, you’d probably need 3” lines. Maybe keep existing for circulation and add a circuit for new filtration?

2. Pool pump won’t do too well in pond application. Check it’s power consumption and compare to an efficient pond pump.Being in Cali and your energy prices, you’ll probably want the pond pump.

3. Bog is good enough for complete filtration if sized properly, but I’d hang onto the pool filter (sand filter?) and use it as a fines filter if water gets cloudy.

Thank you (and everyone else) for all the advice! The plumbing is ~2.5", so I think I'll try to use it for now, if it's too small I'll just do the other plan of making a whole new intake anyway.

The pool is roughly ~17000gal (or so I've been told) so I assume I'm looking at at least 8500gph of flow.
Definitely seems like a new pond pump is in order, I think I would be looking at an external one?
I'm planning to have it inside the poolhouse, just above the waterline; is this doable? From what I understand it's more efficient to have pumps below the waterline, but this would mean new plumbing.
(Which is probably doable, but not without quite a lot of digging. The poolhouse has a concrete base.)


Another thing I'm worried about is the drain clogging with debris; it hasn't clogged before (due to the skimmers), but with the increased flow I'm not sure. Should I add some sort of extra cover over it to block large bits?

I'm going to get started on moving the deck and digging the bog hole, then I should be able to start on the more 'fun' stuff. It might be a while but I'll post an update when stuff has progressed further.

Thank you all!

 

[combatwombat]

The pool is roughly ~17000gal (or so I've been told) so I assume I'm looking at at least 8500gph of flow.

At that size, you could probably get away with less turnover, but 8500 would be a good, safe figure to shoot for if the bog is properly constructed and you plan to keep the fish population low.

Definitely seems like a new pond pump is in order, I think I would be looking at an external one?

You already have the pump house and plumbing for it, so yeah, I'd go for an external.

I'm planning to have it inside the poolhouse, just above the waterline; is this doable?

Totally doable. Done commonly. You will need a check valve at the pond end of your intake plumbing and a leaf basket or a capped tee fitting at the pump to allow you to prime the pump for startup. Efficiency between a little below and a little above water line will not be substantial.

Assume you already have this kind of set up with your pool pump since you're re-using the same space.

Another thing I'm worried about is the drain clogging with debris; it hasn't clogged before (due to the skimmers), but with the increased flow I'm not sure. Should I add some sort of extra cover over it to block large bits?

Sorry, what drain are we talking about here?

I'm going to get started on moving the deck and digging the bog hole, then I should be able to start on the more 'fun' stuff.

Good luck!

 

[wamil]

Sorry, what drain are we talking about here?

The pool's existing drain. It's in the deepest part of the pool, so I'm worried about larger debris (pine needles, leaves, etc) accumulating and clogging the intake for the bog.

 

[addy1]

You could get some sort of wire basket like a colander, large, put it over the drain, held in place with some rocks. That would increase the area that would get clogged up. The 5 gallon bucket I have around my pump intake, drilled full of holes, gets plant plugged I just sweep it off now and then.

My pool in AZ had more than one water intake , the bottom drain and some side pipes.

I have a lim dragon pump, been running for over 15 years now (off in the winter) easy on the bill and has great flow. I am impressed with it.

Dragon Series Pumps - W. Lim Corporation Pumps - Pond Pumps External - Pumps

One of the Largest Selections of Japan's Most Premier Koi and Pond Supplies

usakoi.com

 

[combatwombat]

The pool's existing drain. It's in the deepest part of the pool, so I'm worried about larger debris (pine needles, leaves, etc) accumulating and clogging the intake for the bog.

Got it. I must have missed a detail along the way. Are you not planning to line the pond? What size is the plumbing on the bottom drain? Is it gravity fed to a settling chamber/sieve or is it pump fed—where does the water go now? You're still going to have a skimmer, yes?

 

[Laaf]

I have thought about converting a pool to a pond. Since the filtration system is entirely different, I have thought about abandoning the pool circulation system and dropping new pumps that pull water to the bog, that waterfalls back into the pond/pool. Perhaps also making a separate waterfall separate from the bog for aeration and to be pretty and make nice sound with a second pump. I would hide the cords and tubing with plants and/or rockscaping. Since the bog is the filtration system, the pool filters are no longer needed. I agree with you that I would not want the drain at the deepest part to be where water is being pulled from...........seems it would clog so fast. The skimmer could be useful if it could be used to get floating debris out. But it also seems it could suck pond animals in. Can the existing pool equipment be used without the filter, just to move water?

 

[wamil]

Are you not planning to line the pond?

I'm planning on using a flexible liner for the to-be-constructed bog, but I'm just going to keep the pools original concrete.

What size is the plumbing on the bottom drain? Is it gravity fed to a settling chamber/sieve or is it pump fed—where does the water go now? You're still going to have a skimmer, yes?

I assume it's the same ~2.5" plumbing as shown in the pictures of the pump/filter area, but this pool was built a while before my time so I don't know every detail. From what I understand, the current arrangement is the following:

(There are a few redundancies due to the pool being built in the 80's and being serviced by varyingly-competent contractors)
i.e. it's pump-fed, no settling chamber that I know of.
The pool already has 2 built-in skimmers on the edges under the coping, I figure I'll keep just keep using those.

This is what I'm planning to convert to:

The the features marked in teal will be new plumbing, black is the original. I will basically be disregarding all but one of the existing pipes, for now.

Based on some things others have said, I plan to put some sort of colander-esque structure over the the drain in order to block debris.

 

[combatwombat]

Cool. Going to be a great project. With a 2.5" line from your main drain, pump fed is probably your only choice, which is fine. Will just make the bog a little less efficient.

I'd probably avoid the colander over the drain until you actually end up with clogging problems since the whole point of a bottom drain is to get settled solids off the bottom without any manual labor. Consider sticking an air stone on top of the drain. Will give the drain a larger effective sweeping area.

I'd also recommend reusing the jets if possible. Given the location of the skimmers and drain, the pool was—I'm sure—designed to be a complete system that would get debris from one end to the other where the skimmers/drain can collect it. Without those jets—and the bog being on the left—the whole right side of the pond will lack any meaningful circulation and could create a large dead zone and an area that debris collects. The jets would fix that.

Main issue w/ existing jets will be size of plumbing. If it's 1" all the way back to the pump, that will likely be too small to move the kind of water you need to move efficiently with a pond pump. If it's possible, I'd dig up the main line and upsize it to at least 2".