I have decided to rebuild my existing 8500l pond due to the massive leakage of water. I am using the same area, as this is next to my braai area and will use most of the old structures. I will dig to 2m, but the concrete slab will make the pond shallower. I also want to re-plaster the settlement chamber.

Some photos:

As it was
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Empty pond:

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Will start digging on Saturday. Please advise as I go on.

Albie

Are you keeping the same dimensions and just going deeper?

Yes Wayne, there is just no other space. It is next to our stoep/braai area and the swimming pool is just next to it. Wish I could bigger to the sides, but there is no space- future project!!

While the fish are in the portapool, is there any suggestions to heat the water for this month, without paying a fortune? Current temp already sitting between 13 and 15 and they are basically not eating.

We are digging on Sat. Will post pictures. I am just not sure what is underneath the black cement layer.

Keep well
Albie

Why do you want to heat the water?

Just thought that if the water is a bit warmer, I might get them to eat more for at least the next month and grow faster?? Was just a thought

For me at this stage size is important (!?), since I have lost my two biggest fish. Biggest one only about 50cm

I would not heat up the water. While the fish are in a portapool, give as little as possible food and do regular water changes. The immune system of the fish will be low and they will be under stress. They do not need to eat now.

You can catch up on growth when the fish are back in their new pond.

Get yourself one or two larger fish, but wait untill you have completed your new pond and it becomes mature and naturally warmer again.

From what I can see , you don't have a bottom drain only a double ended pipe?

I dont know if it will be possible but i would advise a relook at the water flow in the pond.

You have the water fall. venturi and skimmer all on one side of the pond. Im not sure how efficient it is as i pressume that the waterfall and venturi will push the leaves and other surface debris away from the surface skimmer.

No bottom drain but i am sure that will added this time around. Something that you might want to consider is a aerated bottom drain. It really helps to clean the pond and is also beneficial to the fish.

I just need to mention that I have connected 2 of my biofilters with the portapool. I will stop feeding and do water changes, but I am not so sure that there is so much stress?? (The sand filter, UV light etc has obviously stopped

Wayne, the water flow is actually quite good- it circulates from the venturi all around until it reaches the skimmer. (I use a black PVC pipe to dampen the effect of the waterfall). When Pieter was here, we really checked that there are no "dead" areas in the pond.

Up to now, I have used the bottom pipe to directly go to the sand filter. This does cause some problems, as I need to keep my sand filter quite clean, but it works. I empty the basket frequently and stir the sand weekly.

The bottom pipe is joined just before the pump by a pipe coming from the sedimentation chamber.

This works as follows:
Water leave the top of the pond, land in the bottom of the first chamber, then up over a wall and get sucked from halfway in the second chamber.

Hope this makes sense.

From the sand filter, it goes the usual route-UV light and high pressure bio filter. I have furthermore 2 submersible pumps that filters water through bio media, water plants, etc and back into the second chamber of the sedimentation chamber.

I wish I can install a bottom drain, but the chamber is right behind the waterfall. So, the chances are that I will need to keep the current system, but will hide the pipes under cement. But we still have time, as I will only start to build in the next couple of weeks. So, if there are other suggestions, let me know.

Just to mention, my water is always as clear as can be with the tests fine.

Starting to break/dig tomorrow. I am not sure what to expect!!, as I inherited the pond. Will post pictures and please comment.

Thanks
Albie

Well, we started and hit a 10cm bottom. This is how it looks now.

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That is going very quick. Im impressed.
If you can remove the steel nicely you will be able to reuse it.

But surely you can use the exciting piping and connect a bottom drain to it. Maybe you can connect a pre-filter between drain and sand filter to keep the big pieces away from filter; you don’t need to rebuild everything behind waterfall

This is part of my filtration system behind the waterfall (not so neat as some of those that I have seen!);

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The "bottom drain" meets horizontally with the pipe from the sedimentation chamber (that drains water from the top of the pond to the bottom of the 1st part of the chamber and then over a wall into the 2nd part, from where it meets the bottom drain water).

I know this is not how bottom drains should work. ( Do you think I should install another filter before the water reaches the basket of the filter?)

Then this go a usual route- via the pump and basket, to the sand filter, UV light, bio filter and back in the pond.

This is in addition to two other bio filters, one of these is the box to the left of the photo. (As well as a home made trickle tower, a container with water plants, etc)

This the container that I used for water plants and some bio media.

I thought I could just as well build a permanent structure with bricks now (water enters through the bottom, through bio media, via plants and back in the sedimentation chamber)

Any thoughts on this?

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So , I want to keep this "bottom drain", unless there is a better suggestion. I will bury it in the concrete.

Wish I could have a 110mm one, but reducing the pipe to my 50 mm pipe might/will cause problems??

So I thought of keeping the 50mm pipe from the bottom, with a filter cap. (Any opinions on this?)

Albie

I need urgent advice please.

As you know, I plan to go one meter deeper; but I'm insure whato do with the existing walls:
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What do you think:
1. Leave the wall, go one meter deeper and build a new wall on the inside of the old wall.
2. Break the wall and rebuild from 2 meters down.
3. Excavate under the wall and build from below until it joins the old wall (?possibility of cracking at the horizontal joint)

I prefer option one, although I will loose some space, but then I go deeper. I'm just scared what I might find behind the wall next to the prefab/neighbours.

If I use option 1, I will make sure that I have a straight vertical line

Albie

I guess it all really comes down to: how to build the walls without having leaks. I think option 3 is out too much risk there.

If it was me i would go for option 2 but option 1 is just as fine as long as you are willing to loose the water volume.

What about having mixed solution - use option 1 and 2. Use option 1 where your neigbours wall is concerned and take out the existing pond wall on your side and next to the pool.

How thick are you going to make the walls?

Remember when you go 2 meters down you cant just have single brick walls the presure and weight of the water will crack it with ease. You really need atleast a double wall or 20cm concrete block wall. Although it is propably not required i will also recommend steel in the walls and floor.

Thanks Wayne

I will see how the day progresses

If I go for option one, I will build 1 wall underneath the old wall, and put concrete behind wall one. Then I will leave a space between the 2 walls from the bottom up, approximately 1.8 m. I will fill the gaps between the walls with concrete.

For waterproofing, I will stay away from butamen. I thought of mix the plaster with salt and Coprox. Once completely dry, I will use Hydro Seal.Pieter de V swears by it- it has a cement base that penetrates the plaster.

But I might still go for option 2, but thought we should dig a bit today.

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Thanks

Albie

Will try to keep everyone posted. What do you say Pieter, Paul??

Just another point

The guys thats working in the pond, feels that the sides are not make of brick, but of concrete, re-inforced with steel. So that might be difficult to break.

End of the 2nd day of work:

Only at 130cm at the deepest:

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Look at the bottom of the side- it does look like concrete

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Hi Albie,

The best ratio regarding salt and cement is 25kg salt per 1 bag cement.

Pieter
Would you add the salt to the concrete mix as well?

Would do you think about Coprox in addition to painting the pond with HydroSeal?

Regards
Albie

1. The next step is the bottom drain, which will need to go directly to the pump filter via the basket.

So, I cannot use a 110mm pipe, as I cannot go beneath the waterfall:
Which one will you chose to link up with a 50mm pipe:

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B. [You must be registered and logged in to see this image.]

The pipe will be in the concrete and join with the swimming pool pump:

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Next is the concrete- I want to throw on Friday:

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Depth in total is 1.6m.

Should I throw a flat slab of 15 mm and later add concrete to create a "fall" to the drain, or do it all at once? I plan to put plastic under the slab.

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I plan to build 2 walls- two for the lower 85cm with a space in between, and one above to the surface. These spaces. The top half of the existing pond is built from concrete an we could not break it.

Then I thought of mixing the plaster, with salt and Coprox and paint with ydro seal. This will surely make it waterproof.

Any comments will be useful, as I am very new to this.

Will later ask about the inlets as some suggest a Venturi as well as a deeper inlet for proper circulation.

Thanks
Albie

Albie, I would have made a plan to take the 110 mm pipe all the way to the "sediment" /"settlement" chamber. What a waste to reduce it to 50mm and it is never a good idea to suck directly from a bottom drain. Can't you lift the paving next to the pool and go around the waterfall with a 110 mm pipe?

As far as the waterproofing are concerned, Pieter's suggestion of 25kg salt/bag of cement mixed with Coprox should do the trick. I normally use Sikalite and salt with my mixture and paint afterwards with Coprox.

Hi Paul

I wish I could get a 110 mm pipe to the bottom of my chamber, but see how full it is and the chamber has a concrete floor- tried to break it. The path between the pond and pool is also quite narrow. Any other suggestions?
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I just thought of something else- I have a submersible pond. I will be able to suck water from that bottom drain close to the chamber into the 1st chamber (I thought of trying to create a type of vortex effect in that one, sides built round and the bottom cone shaped. The overflow will be in the second chamber.

Just three questions:
1.Should I mix salt and Coprox with the concrete?
2.What do people think- should I do the slab all at once, or first throw a flat one and a few days later the slope?
3.Will 15mm be enough- depth now 1.6 m

Albie

Albie,

Paul is correct with:

Quote :

As far as the waterproofing are concerned, Pieter's suggestion of 25kg salt/bag of cement mixed with Coprox should do the trick. I normally use Sikalite and salt with my mixture and paint afterwards with Coprox.

Regarding the bottom drain; Ultra-Zap could help you there. Please don't use the drains and fittings in your photos!
Phone Bruce at Loolilocks, he will help you; 011 918 2262 or Email [You must be registered and logged in to see this link.]

Don't mix Coprox with anything, apply it onto the "plaster" according the instructions. You may apply Flash Harry (six coats) afterwords.

All concrete work should be done in one go, to avoide cracks. A floor of 250mm should do the trick.
The section between the floor and "wall" should not be square, but
round-off .

Admin wrote:

it is never a good idea to suck directly from a bottom drain.

I've seen many setups that do suck directly.. Including one by Pieter De Villiers..

Why do you say it is not a good idea?