Thread: Concrete base or not?

Hi, I'm getting rid of our current pond and building a new one further down our garden, the plan is it's going to be block built 3.5M x 2.5M x 1.5M deep (80cm below ground, 70cm above). I plan on using underlay and a pond liner.
My question is, will it need a concrete base as I've had 2 quotes from groundworkers. One is with a concrete base and the other without.

Originally Posted by john1

Hi Mickey,
I would say no you dont need a concrete base,but you would need a solid concrete ring for your blocks.
Bottom drain in first and surround the pipe with concrete to stop it heaving.
Obviously need underlay on the base,the earth will keep the pond a bit warmer in the winter as opposed to useing concrete.
Hope this helps.

Cheers, I'm not putting a bottom drain in due to the fact our current one had one, the pipe from it split under the pond and we woke up to 12 dead fish.

I'm going to set up the retrofit version of a bottom drain that will have the pump controlled by a float switch. Cheers for the advice about concrete foundation for the side walls, I suspected as much. Our current pond doesn't have a concrete base but we compacted the ground below then underlay and liner straight on top so going to do the same again.

You don’t need to have a concrete base, just as long as the earth is well compacted and the liner is protected from any sharp stones.
But as John said, you do need a solid concrete foundation for the blocks to be laid on. This can be either done at the bottom of the pond as a strip foundation or at ground level as a ring beam, which was the option I used because it was cheaper as you don’t need as many blocks. I insulated mine which helps with heat loss and also protects the liner.
I would seriously reconsider installing a bottom drain as it is a much better option than a retro fitted one.
I’ve uploaded some pics of my build.
Good luck with yours.

Originally Posted by Martin59

You don’t need to have a concrete base, just as long as the earth is well compacted and the liner is protected from any sharp stones.
But as John said, you do need a solid concrete foundation for the blocks to be laid on. This can be either done at the bottom of the pond as a strip foundation or at ground level as a ring beam, which was the option I used because it was cheaper as you don’t need as many blocks. I insulated mine which helps with heat loss and also protects the liner.
I would seriously reconsider installing a bottom drain as it is a much better option than a retro fitted one.
I’ve uploaded some pics of my build.
Good luck with yours.

Unfortunately I can't see your pics, after losing our fish before I know I'll always be wondering about the bottom drain pipe. We lost a 11lb and 9lb Koi and it was gutting. Any advice on how the pipe should be laid in the ground to protect it if I do it again? The bloke who built ours looked to have done it right but perhaps not.

Laid correctly, there is absolutely no issue with using 110mm waste pipe. After all, it is designed to be laid up to 10m down with a design life of 100 years.

Lay it on a good 100mm bed of 10mm pea shingle and cover it with the same. Ensure the shingle is flush with the base of the pond, then lay your underlay and liner.

The pressure at the bottom of a pond is quite low - at 1.5m it is 2.3 psi, and don't forget that the pressure outside the pipe is the same as the pressure inside the pipe.

Waste pipe is adequate but pressure pipe has come down in price so much there is no point in using waste pipe A bottom drain is a no brainer

I find that keeping Koi is all about advancement, but by not fitting a bottom drain you are going backwards!!

My pond is pump fed but I would give anything to have a bottom drain, but as I have said before, at 81, I cannot justify the work & expense involved.

Some years ago I fitted a retro bottom drain but found it no better than having the pump only, I sold it on years ago.

If you do decide to fit the retro drain slope all 4 edges towards the drain to allow mots of the waste to roll towards it & also be prepared for a lot of extra work in keeping the pond clear & healthy.

Best of luck,

Brian.

Originally Posted by john1

I would be doing it as Martin said and definitely do a bottom drain,not too hard to do and folk on here can help you through that part.

I'm definitely not going to be putting a bottom drain in, it was the solvent weld on an elbow that failed and popped the pipe out, I've been a heating engineer for over 35 years and unfortunately the modern solvent weld glues and fittings are far inferior to how they used to be due to companies using cost cutting methods, I've designed a pipework system that will efficiently collect water from several areas on the base of the pond without the risk of fractured pipework..cheers for your thoughts as it's a minefield 🤣

'm definitely not going to be putting a bottom drain in, it was the solvent weld on an elbow that failed and popped the pipe out, I've been a heating engineer for over 35 years and unfortunately the modern solvent weld glues and fittings are far inferior to how they used to be due to companies using cost cutting methods, I've designed a pipework system that will efficiently collect water from several areas on the base of the pond without the risk of fractured pipework..cheers for your thoughts as it's a minefield 🤣

Originally Posted by Brian C

I find that keeping Koi is all about advancement, but by not fitting a bottom drain you are going backwards!!

My pond is pump fed but I would give anything to have a bottom drain, but as I have said before, at 81, I cannot justify the work & expense involved.

Some years ago I fitted a retro bottom drain but found it no better than having the pump only, I sold it on years ago.

If you do decide to fit the retro drain slope all 4 edges towards the drain to allow mots of the waste to roll towards it & also be prepared for a lot of extra work in keeping the pond clear & healthy.

Best of luck,

Brian.

'm definitely not going to be putting a bottom drain in, it was the solvent weld on an elbow that failed and popped the pipe out, I've been a heating engineer for over 35 years and unfortunately the modern solvent weld glues and fittings are far inferior to how they used to be due to companies using cost cutting methods, I've designed a pipework system that will efficiently collect water from several areas on the base of the pond without the risk of fractured pipework..cheers for your thoughts as it's a minefield 🤣

Sounds interesting, so your solutions will be weld free?

I get you will not be wanting a bottom drain, but a failed joint on a previous one is very very rare, even on here carried out by DIY enthusiasts, I am not sure if I have heard of another failure, I would blame poor preparation and application by the previous installer rather than inferior products, but maybe that's just me

Anyway, really looking forward to seeing your design and build

Originally Posted by dbs

Sounds interesting, so your solutions will be weld free?

I get you will not be wanting a bottom drain, but a failed joint on a previous one is very very rare, even on here carried out by DIY enthusiasts, I am not sure if I have heard of another failure, I would blame poor preparation and application by the previous installer rather than inferior products, but maybe that's just me

Anyway, really looking forward to seeing your design and build

I hadn't heard of another failure either until it happened to me and I've heard of several since it was a solvent weld fitting that popped off. As a heating engineer of 35yrs I'm seeing it a lot more now as the modern glues and fittings are inferior it held fine for 14 years and then an elbow popped off 😩.

My solution is an external pump drawing through 3 separate pipes through the back of the top of the pond to separate drains located at the bottom.
The pump is going to be mounted at a height that's approximately 1m up the side so even syphoning won't drain it considerably.

Going to be a railway sleeper pond with window now 😁