Bottom Drain - Installation and Freezing

[Andy41]

Hi Guys,

I've got a couple of questions about bottom drains and how they cope over winter.... i've never worked with these before, so bear with me if some of the questions are a bit daft.

1. Can anyone provide a link to a good guide on how to install a bottom drain? It's clear i need to make a hole in the bottom of the liner at the lowest point and run a pipe underground to the pump, but what is the best way to secure it etc - concrete pad, screws, fixings etc?

2. What stops the smaller fish from being sucked into the bottom drain?

3. I live in an area where it can hit -20C in winter. The water in the bottom drain pipe is going to freeze.... how do you avoid the pipe splitting? Obviously the choice of materials is important, PVC probably? and also disconnecting the main pump during winter and leaving the bottom drain pipe open to allow for water expansion.... any other ideas?

cheers,

Andy.

 

[DoDad]

How deep is your pond?
There is a gap of about a 1/2" between the dome and the bottom drain. If a fish is smaller than that and your BD goes to your pump you can say goodbye to the fish.
If your filter system is gravity fed and you have a settling chamber you just retrieve your fish and put it back in the pond.
http://www.koiclay.com/diy/pg4.htm

 

[Andy41]

Hi DoDad,

The pond doesn't exist yet, which is why i'm looking around for all the tips on how to build this.... when it is built it should be about 5' deep at the deepest point.

The link you provided is *exactly* the type of guide i've been looking for :frown:

Some of my fish are small... if they turned on their sides they could get through a 1/2" gap.... i'm going to have to think about the filtering arrangements afterwards then.

Cheers,

Andy

 

[Shdwdrgn]

Is there a reason why so many folks talk about using bottom drains in their ponds? The best I can figure out, perhaps this is a key difference between using an external versus a submersible pump?

 

[Andy41]

I'm using a submersible pump in my current pond..... it works ok, but it also has a tendancy to clog after a while. Also, because it's sat on the bottom of the pond you will always have a small gap between the intake and the floor where sediment can build up.

So this time around i wanted a way to try and remove that sediment, and the bottom drain seems the best solution. However, the downside is more work in the design of the pond, and expense / time with plumbing.

Also, having the pump external will make maintenance a lot easier.

Cheers,

Andy.

 

[Shdwdrgn]

Ah that makes sense. For my rebuild, I've been happy with my submersible, however I will be using a rubber liner for the last pond this time, so I plan on digging a deeper spot for the pumps to sit in. That will give the sediment a place to settle in to, and hopefully help the pumps pick up the worst of it.

I just really can't bring myself to cut a hole in the middle of the liner...

 

[DoDad]

Let's look at it this way.
I build a room with no way out and it has no toilet.
I give you all the food and drink you want. What happens after one year?
Bad bacteria begins to grow and any nicks or cuts you get are soon to be infected.
With no treatment from the one who feeds you, they end up burying in their flower bed.
But then if you had a toilet no problem.
A bottom drain eliminates all of this.
If your bottom drain goes to the pump first it get pureed before it goes to your filtration.
It's harder to filter out and a lot of filter cleaning.
If it goes to a settling chamber and on into the bio filter and then pump no problem.
In the Spring when your water starts to warm the bad bacteria in the crap on your pond's bottom becomes active before your fish immune system kicks in the bacteria has their fun.

 

[kirscp]

How deep is your pond?
There is a gap of about a 1/2" between the dome and the bottom drain. If a fish is smaller than that and your BD goes to your pump you can say goodbye to the fish.
If your filter system is gravity fed and you have a settling chamber you just retrieve your fish and put it back in the pond.
http://www.koiclay.com/diy/pg4.htm

He is correct, My bottom drain goes into a 500 gallon settling chamber, I've had 12"+ koi go through the bottom drain and I'm always pulling babies out of the settling chamber. Takes them a few times to learn to stay away. If you have it connected to a pump, you will lose a lot of fish. Make sure your plumbing is large enough, I went with 4", and make sure you don't have a lot of 90 degree angles. If it gets clogged, you will need to be able to unclog it.

My biggest issue is string algae. It'll wrap itself around the bottom drain and restrict the flow of water. Normally once a month that means I get to go for a swim with the fish ... sometimes I swear the babies have TEETH!

I will say, I would never go with a pond without a bottom drain!

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I don't have a single pump in my pond. I have a pump in my settling chamber and one in another chamber where my skimmer flows to. They way I have everything set up, I can only lose 1 foot of water off my pond, if a plumbing issue comes up. I don't have to worry about a pump draining my pond for me.......

 

[DoDad]

I had string algae once and it restricted the flow of water to the BD.
I control the algae now and have no problem with it.

 

[CometKeith]

DoDad, I think you have clearly made the case for a bottom drain. I am thinking of enlarging my pond this Spring and now realize I need to install a bottom drain, What is your opinion of skimmers? How important are they?

 

[addy1]

Some like them some don't. I have had one on each pond with the ability to turn it off. When the leaves are dropping, or if we are getting a flower dump I flip it on to get the stuff off the surface. Then flip it off again.

It does cause issues with sucking in the food, lil fish, floating plants, but it does clean the surface nicely.

I put mine, on this pond, on the downwind side. The wind nicely blows most of the leaves right to it.

 

[DoDad]

I wouldn't build a pond with out a skimmer or Bottom drain.
My preference in skimmers are the savio.
No flimsy plastic and built like a tank.
The skimmer removes leafs and any film on the water.
But the bottom drain is most important of the two.

 

[DoDad]

I made a styrofoam food blocker and it works very well. I can throw food in front of the skimmers weir and no food gets in the skimmer. If I forget an leave it the koi knock it down and eventually it makes it in the skimmer.























i

 

[addy1]

I wouldn't build a pond with out a skimmer or Bottom drain.
My preference in skimmers are the savio.
No flimsy plastic and built like a tank.
The skimmer removes leafs and any film on the water.
But the bottom drain is most important of the two.

I bought a swimming pool skimmer, hayward, it has a huge weir, built like a tank and a large leaf basket.

 

[taherrmann4]

Is it possible to add a bottom drain to an existing pond without draining the pond and cutting into the liner. If so how would you go about doing this?