# Do I need to use rebar?



## Mark in Poole (19 Mar 2017)

Hi all and thank you for adding me to your site. 

I am building a sunken cement pond 10 x 8 x 3.5 feet. My question is do I need to use rebar in the construction? If so is that just for the base or the walls as well? To one side of the pond there will be a raised veggie filter with a waterfall back into the pond.

I also have a pile of patio slabs I need to dispose of so I intend burying some of those at the base of the pond to add stability. I'm not sure if this is a worthwhile option or not? 

Many thanks,

Mark


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## frederick thompson (19 Mar 2017)

Mark in Poole said:


> Hi all and thank you for adding me to your site.
> 
> I am building a sunken cement pond 10 x 8 x 3.5 feet. My question is do I need to use rebar in the construction? If so is that just for the base or the walls as well? To one side of the pond there will be a raised veggie filter with a waterfall back into the pond.
> 
> ...


Hi mark if you read my thread you will see i had a pond built in the last year.
Are you putting a bottom drain in the system. If your putting koi in the pond. I would advise this. Or any fish for that matter.

My base was 6 inch thick with rebar and plastic fibers added.

Also how are you building your walls. Normal blocks built like traditionally bricks and mortar 

Or are you doing it dry stacking
If dry stacking you need to fill the blocks internally.  And rebar added. This is called back filling.
In your first 3 courses you have to drill into the base with rebar . And cement in.To tie the blocks to the base. If build tradional way brick and cement then rendered. Or use of celotex then fiber glass

Mine is above ground with blocks and house brick tied with brick ties. With 2x windows built in. Bottom drain and skimmer. Upper pond lower pond 6 feet deep. Fiber glassed.
Hope this helps mate. Read my thread you might pick up some tips on there mate. Also any questions.  Just ask away mate

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## Mark in Poole (19 Mar 2017)

Thanks for getting back to me Fredrick,

Ok so here goes for my naivety. On the videos I have seen most people have shaped rebar around the base and walls then simply cemented to that.  I only thought it needed to be bricked if it was going to be above ground level? No problem though I can brick if I need to.

My plan after that was to render with fiber, burn off excess then paint with rubberized pond paint.

As far as a drain goes surprisingly enough I’m totally naive there as well . Luckily I’m still in the drawing and not the building stage. Ok stupid question for all to laugh at… If I put a drain into a sunken pond where does it drain to?

P.s. Please don’t answer Oz I already thought of that one.
I will check out your thread now.


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## Mark in Poole (19 Mar 2017)

Understood (I think).... The bottom drain isn't technically a drain, it goes back to the filter? If that is the case yes I will have a bottom drain once I find the best method of fitting it.

P.s. Don't be fooled there is hope!


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## martin-green (19 Mar 2017)

*Intro*:
Hello Mark in Poole.
_Building a pond is easy, dig a hole shove in a liner, put water in it job done_.

If only it was that easy. A pond when built correctly is only built once, so don't rush into it, do some more research and if you can go and have a look at some ponds.......

*Regarding what you have so far said*:
At 3.5 feet deep your pond is reasonable but bear in mind that the excavation will need to be deeper to allow for the base.
You can use the paving slabs if you smash them up and use them as hard core. 
A sunken drain (Known as a bottom drain) is there to collect fish waste, this fish waste then goes to your filter system - usually to a vortex chamber (Giant funnel with high sides) and of course, the bottom of the pond must slope to the centre where the bottom drain is. 
You don't have to have a bottom drain, but if you don't its more work since you have to clean the pond floor (You really can get pond vacuum cleaners that will do this, but the best are not cheap, and they need to be pushed around like when you vacuum a carpet) 

*Fish*:
I feel I should point out that your pond will be fine "for some gold fish" but too shallow for KOI, and KOI are expensive fish to look after. (Even a well looked after goldfish can live 15+ years) 

*Wall coating:*
Some years ago now, mate of mine got hold of some "water tank paint" (As used in commercial water storage tanks that hold drinking water) he painted his newly dried out rendered pond walls (Two coats over several days) filled with water and dechlorinator water tested a ok, in went the fish, less than a week later all the fish were dead. Yes, the water tank paint was genuine, and any water stored was fit for human consumption, but that was the problem, it was safe for humans, not fish. 
So he spent the next couple of weeks getting it sandblasted off and he had the whole pond fibre glassed. 

You can get a fish friendly concrete sealing paint, its called g4 (Available in black, blue or clear)

*Filtration:*
Your filtration need to be able to cope with "fish waste" of any fish you have, and bear in mind happy fish will breed. Most (not all) people have a veggie filter as well as the "normal" filtration. It may be something you want to consider.

*UV*
You are probably not yet aware of such a thing, but in short it keeps your pond water from turning green (pea soup) brand is your choice, but size depends on flow rate to your filters.

*Pump(s)*
You need a pump big enough to supply the filtration system, in short you can turn a big pump down, but you can't turn a small pump up. And two pumps are always better than one.

*Electricity*
You will need an electricity supply for the pumps uv, lights etc. You can get "dubious kits" that enable you to DIY, but I would at least consult an electrician, and what ever you think you will need, you will always want more.


*Thoughts*
Doing it all your self, will take a lot of time, but when its finished you can stand back and say "I did that" and be proud. Do several drawings, sit and look at them, mark out the area in your garden with a rope or hose and look at it for a week or so, look at it from all angles, you can easily move a hose or rope now, you can't easily move a hole. And don't build it near any trees 

And that's just for starters. 

There are a few of us on here who can try and help, the above is how I see it.


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## Mark in Poole (19 Mar 2017)

Martin that is fantastic thank you. 

I intend to continue my research so all this info coming in is massively appreciated and will be taken on board. 

I definitely want to keep Koi so I will amend the size of the pond where necessary.

As far as the veggie filter goes the "expert" in the local shop told me that this was in place of a filter/ uv filter and not an addition. I assume this isn't the case?


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## frederick thompson (20 Mar 2017)

Martin has given you some good advice there.
When you put a bottom drain in you also need air. My bottom drain is a spindrifter. So when you run your 4 inch pipe under your concrete base you also run a 1 inch pipe as well . And this will run your air from the filter house out the bottom drain. Mine has a diffuser one at each end of 1 inch pipe on the stem is a connection so you cut a piece of air pipe put it on stem and diffuser.  Air runs down 1 inch pipe. Into airpipe. And out your dome.
Basicly this circulate s the water in the pond plus aireation. Then you want tangible pond returns. TPR built in to circulate the water on the bottom of pond and drain sucks the muck to filter. Thats basicly how the cleaning system works. I never have to clean in the pond its self. The system does it all itself.  My last pond i was vacuming it out every other day. This one lts done right so no need.

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## frederick thompson (20 Mar 2017)

Also mark my last pond built is 6 feet deep. Thats the one mistake i have made. If i had to build again it would be 5 feet deep. I feel 6feet is to much. Reasons. Trying to catch fish for scrapes is one.
Reason certain  fish its to deep they have fish bladder problems. Idealy 4 and ahalf feet to 5 feet is perfect. 

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## frederick thompson (20 Mar 2017)

Before i decided to have my pond  fiber glassed.  I did a lot of research on pond paint. The best i found was the p range from the east riding koi co. P1. Very exspensive.  They all are. G4 was the next best one.
Also very exspensive.
Thats why i had mine fiber glassed . Saved a few more pennies to get it done.
Lasts longer. Most ponds with paint and rubberised have to keep redwing them

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## Mark in Poole (20 Mar 2017)

Fantastic Fred it’s all coming together. I wasn’t sure how I was going to do the aeration either so you have answered that already. My knowledge on fish is actually reasonable high but clearly I am a total novice at building a pond.

So please correct me if I am wrong. The flow... Bottom drain – Filter (I’m assuming this will be out of the water, hidden in the rockery) – Veggie filter – Waterfall

Great response Fred and Martin thank you.


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## frederick thompson (20 Mar 2017)

See i don t know what your plan is. Bottom drain sucks water to filter. In my case. Draco drum and nexus.
It comes down the 4 inch pressure pipe to my nexus gravity feed. Into my nexus filter.  The pump is after the nexus so it sucks water out and pushes the water o
n to my uv all in the same return pipe. To my upper pond to water shoot. Thats it.
As the pump pulls water it automatically gravity feeds back from pond to filter 
In my case i have 2x lines. 2x pumps. I have a skimmer line to clean the top surface as well. With uv on that line as well.and this returns through my TPR. Tangible pond returns. Which cause a under water currant to circulate the water. So eventualy the muck either goes in bottom drain or skimmer. My skimmer line has a ultra sieve 3 and uv on the line. Plus pump. This is also gravity fed and pump after the sieve. Back by return to tpr. My last pond was inground no bottom drain. My pumps where in the pond to water fall. Nightmare cleaning all the time. 


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## frederick thompson (20 Mar 2017)

My top pond is cleaned with  plants. But if your having koi. You will need machanical filteration before the veg filter. Veg filter will not be enough on its own. It will take agesvto mature for a start. It will be a big help further down the line.

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## Mark in Poole (20 Mar 2017)

Why is it not surprising that I never even thought of a skimmer! . Thanks again Fred very helpful indeed but I need to google a little of that as I'm not quite sure what it all is. Brilliant though, it's all good planning I do not want to do this twice.


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## frederick thompson (20 Mar 2017)

Mark in Poole said:


> Why is it not surprising that I never even thought of a skimmer! . Thanks again Fred very helpful indeed but I need to google a little of that as I'm not quite sure what it all is. Brilliant though, it's all good planning I do not want to do this twice.


Thats why i mentionedvthe skimmer. I will take some photos for you to give a btter idea.


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## frederick thompson (20 Mar 2017)

Right here is photo of my pond. Upper pond back to pond lower




Next bottom drain and air



Notice on surface how air pushes to sides for skimmer thats the skimmer far end with grey grill




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## frederick thompson (20 Mar 2017)

Inside skimmer box



Then along to filter house



4 inch pressure pipe and 4 inch ball valve then into my ultra sieve






So thats how it comes from pond to filter.

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## frederick thompson (20 Mar 2017)

Now how it returns back to pond
Bottom pressure pipe to pump






Then to uv



Then to tpr 2 foot of pond bottom



They run underground to inside my pond. And that circultes water

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## frederick thompson (20 Mar 2017)

My drum and nexus from bottom drain



Thats it cleaning



Then into outer chamber. Which is k1 media for bio.






Into uv 55 grey one. Back to upper pond
Hooe this gives you a better idea mark

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## frederick thompson (20 Mar 2017)

Cheers ian m all the best fred

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## martin-green (26 Apr 2017)

This post is intended for Mark in Poole.

Mark, it has been over  month since your last post, I am just wondering "How is it going?"


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