Ultimate Koi pond renovation

[Rymerdr]

For anyone interested, I've decided to redo my pond.
When I moved into the house the pond was a mud pit (4 years ago). I cleaned it up added a layer of duram pond sealer, filled it added a submersible pump a sand filter a bio filter and UV light. 4 small carp and a few gold fish.

Since that day I've had endless issues and have now decided to redo it properly. The issues have been leaks, leaf litter. I've considered filling it with sand many times, but I've grown quite fond of my fish and would love to give them a better home. But I'd like something that requires a little less maintenance.



The plan is to:
1. Dig the pond to 1.5m deep keeping the original shape (5m diameter)
2. Remove the 2 feeding ponds as they are too shaded to create a bog filter.
3. Install a bottom drain with air diffuser and gravity feed to pre filter (settlement tank or sieve), then to moving bed and bio filter then pump back to waterfall.
4. Add a skimmer that feeds to settlement chamber or sieve filter.


My plan was to use an EPDM rubber liner, but this is proving impossible to source post lockdown.

The only other option is to go concrete.

My thinking is to use a pvc under layer as we have a high water table. Use fibre reinforced concrete about 100mm plus steel mesh reinforcement.

To seal the concrete, I'm undecided. There are cement additive like sika or cemcrete sell a paint on waterproofer (matcrete), or a spray on rubber compund. What would be best?

As you can see in the photo the removed concrete has 3 distinct layers. But there was no steel reinforcement, which is probably why it cracked and leaked.

Tomorrow we begin digging, let's see how deep we get until the water.

Any advice, especially related to the concrete would be most welcome.

Thanks
Darren

[Robbief]

Make sure the big guys dont jump out the holding tank.

[Robbief]

Make sure the big guys dont jump out the holding tank.

Please realize the depth will change a lot, after concrete, water to curbing space etc, go deeper

They supposedly get bigger with depth, also better for them in winter. I have one fish of over 800mm

[Kortgat]

I’ve kept Koi for 25 years now. Have built 5 ponds in that time, the last two were proper. First three were liner ponds.

Forget the liner.

First line the whole area with plastic sheeting. Then put down all your pvc for the bottom drain/s and return/s. Use high quality pvc pipes and fittings. Take care during the solvent welding process. Concrete with proper steel reenforcement. Don’t skimp on the concrete. Then plaster with a Coprox enriched plaster mix. Thereafter seal with a coprox slurry. Forget about all the rubber and epoxy products, they all have a limited lifespan. The Coprox becomes part of the structure.

For filtration, gravity feed is the way to go. Ideally first into a settlement chamber, then into a static medium and then into a moving/fluidized bed and from there return to the pond via DC pump/s. That way you keep your power consumption low. My 25000 l pond consumes 200 watt incl. pump and air pump for the moving bed filter. I used to have a uv running, but due to the good filter it’s no longer necessary.

That’s it in a nutshell. Obviously loads of detail goes into the filter design etc..

[Kortgat]

Oh on the depth, I’d go no shallower than 1.2 meters at the bottom drain, 1.8 or 2 would be better.

[JanL]

One of the contributers with water leaks in a pond is water pressure. The deeper the pond the better the concrete mix has to be. The next waring is the for the drain. I assume you would hace a U connectioc to a mechanical filter. Another small water catchment body next to the pond fron where the pump would pump the water to bio and or sandfilter. If you use pvc for drain purposes the you would experience leaks at the rubber seals. The water body with a 1, 5 m depth put a fair amount of pressure on these seals. So look for another product to engineer your bottom drain. I gave up on mine and sealed it off. Cleaning the bottom then becomes very combersome.

[Rymerdr]

Thanks Kortgat, this is just the advice I was looking for. Coprox it will be, I remember Mad Manny mentioned it a while ago.

As for the bottom drain it will be within the concrete so won't be exposed to water pressure.

Any idea where I can get good quality PVC pipes and fittings in the JHB area?

[4eTouareg]

Nube question: Can't one use a glass fibre pool insert, painted in a dark colour?

[Rymerdr]

I don't see why not. In my research one of the most durable ways of sealing concrete is to cover it with a layer of fibreglass.

Nube question: Can't one use a glaas fibre pool insert, painted in a dark colour?

[Kortgat]

Thanks Kortgat, this is just the advice I was looking for. Coprox it will be, I remember Mad Manny mentioned it a while ago.

As for the bottom drain it will be within the concrete so won't be exposed to water pressure.

Any idea where I can get good quality PVC pipes and fittings in the JHB area?

Yes, go to Astore Africa in Anderbolt Boksburg.

[Rymerdr]

The digging continues, got down to 1m today, another metre to go. Soil is a firm clay, I hope we don't hit water before 2m.

[Graham]

Nice thread!
I’m just wondering though, if you’re wanting to do it properly, why reinvent the wheel? Why not get a pool company in to line it like a normal pool, think it’s called gunnite?
I’m sure it won’t be cheap. But pools last for what? 25yrs or something?

[Kortgat]

Nice thread!
I’m just wondering though, if you’re wanting to do it properly, why reinvent the wheel? Why not get a pool company in to line it like a normal pool, think it’s called gunnite?
I’m sure it won’t be cheap. But pools last for what? 25yrs or something?

It’s very expensive that way. Much cheaper to hand-pack concrete. Hand packed with steel reenforcement will also last forever. Gunnite just speeds up the application process.

[vidalbum]

layer of glass with a flow coat ontop problems sorted

[royjacobs]

I am planning something similar in the near future, very interested to see your progress and results.
Pics please if you don’t mind
Roy

[royjacobs]

Hi Kortgat,
I am not very knowledgeable about filtration systems, but also not entirely ignorant either.
If you wouldn’t mind some pictures or graphics or your explanation on how the best system?
Roy

[JohanMaree]

Rymer

You live in Gauteng. Come visit me and see our system. Been with koi over 15 years.

1.5m is an over kill. Go 600 deep. That is enough.

On camping trip now so cannot write too much detail

[Kortgat]

Rymer

You live in Gauteng. Come visit me and see our system. Been with koi over 15 years.

1.5m is an over kill. Go 600 deep. That is enough.

On camping trip now so cannot write too much detail

Johan, respectfully disagree there. Deeper is always better:

- better temperature stability
- overall cooler summer temps (better oxygen levels and easier to maintain clear water)
- much better ability to slope the pond towards the bottom drain
- koi develop better body shapes if they have deeper water (somewhat debatable)

Shallow koi ponds are almost always ‘contractor’ ponds, not professional well planned setups.

[Kortgat]

Hi Kortgat,
I am not very knowledgeable about filtration systems, but also not entirely ignorant either.
If you wouldn’t mind some pictures or graphics or your explanation on how the best system?
Roy

Sure, pictures won’t show much as everything is in a submerged state, but will try do a sketch and look for pictures when I was building.

[royjacobs]

That will be a great help thank you.
Roy